[¶ 1] Gene Jarvis appeals from an order denying his motion for reconsideration, amended findings and judgment, a new trial, and a stay in his divorce action against Jennifer Jarvis. We direct the judgment be modified, and we affirm the order.
I
[¶2] The parties married in 1980. Two children, Sara and Andrea, were born during the marriage in 1988 and 1992. When the parties separated in 1996, Jennifer Jarvis was earning approximately $7.58 per hour in the business office at MeritCare, and Gene Jarvis was earning $7.25 per hour at Dakota Food Equipment. Gene Jarvis was also earning about $300 per month working at a part-time job, which he quit shortly after the parties separated.
[¶ 3] Gene Jarvis sued for a divorce on April 2, 1996, and Jennifer Jarvis later counterclaimed for a divorce. The parties stipulated to an interim order giving physical custody of the children to her and liberal visitation to him; requiring him to pay $300 per month in child support and $100 per month for daycare in May, June, and July; requiring her to maintain health insurance for herself and the children; and requiring the parties to share equally any noncovered health care expenses for the children.
[¶ 4] The judgment entered after trial granted Jennifer Jarvis a divorce; divided the parties’ marital property; awarded her custody of the children, with reasonable visitation for Gene Jarvis; required him to pay child support of $356 per month; and required each party to pay one-half of “daycare expenses (currently $480 per month); preschool tuition for Andrea (currently $567); the monthly cost for Jennifer providing healthcare insurance for the children (currently $126 per month); one-half of all uncovered medical, dental, prescription, orthodontic, and eyeglass expenses.”
[¶ 5] Gene Jarvis moved for reconsideration; amendment of the findings of fact, conclusions of law, and judgment; a new trial; and a stay. The trial court denied the motion, and Gene Jarvis appealed the denial to this Court.
[¶ 6] The district court had jurisdiction under N.D. Const, art. VI, § 8, and N.D.C.C. § 27-05-06. The appeal was timely under N.D.R.App.P. 4(a). This Court has jurisdiction under N.D. Const, art. VI, § 6, and N.D.C.C. § 28-27-01.
II
[¶ 7] The trial court’s determinations on child custody and child support are ordinarily treated as findings of fact, which are not reversed on appeal unless they are clearly erroneous. See, e.g., Harty v. Harty, 1998 ND 99, ¶¶10, 14, 578 N.W.2d 519. That standard does not apply in this case, however, because Gene Jarvis did not appeal from the judgment, but from the denial of his post-trial motion:
We recognize that the clearly erroneous rule does not apply in this instance because there is no appeal from the judgment, but only from the order denying a motion for a new trial. A refusal to grant a new trial to correct a judgment based upon clearly erroneous findings of fact may, however, be an abuse of discretion. On the other hand, we have observed that the fact that a trial court may have made a mistake in the law when entering a judgment does not necessarily justify setting the judgment aside under a Rule 60(b), N.D.R.Civ.P., proceeding. See First Nat’l Bank of Crosby v. Bjorgen, 389 N.W.2d 789 (N.D.1986).
Kaiser v. Kaiser, 474 N.W.2d 63, 65 n. 2 (N.D.1991).
[¶ 8] We do not reverse the denial of a motion for a new trial unless the trial *87court abused its discretion. Barnes v. Mitzel Builders, Inc., 526 N.W.2d 244, 246 (N.D.1996). Motions to reconsider are like motions to alter or amend judgments under N.D.R.Civ.P. 59. Austin v. Toume, 1997 ND 59, ¶ 7, 560 N.W.2d 895. A decision on a motion under N.D.R.Civ.P. 59 is within the sound discretion of the trial court, and denial of a motion under N.D.R.Civ.P. 59 will not be reversed, absent a manifest abuse of discretion. Id. ¶ 8. A trial court abuses its discretion if it acts in an arbitrary, capricious, or unreasonable manner, or misinterprets or misapplies the law. Id. ¶ 8.
Ill
[¶ 9] Gene Jarvis first contends the trial court erred in ordering him to pay one-half ($63 per month) of Jennifer Jarvis’s medical insurance premiums and one-half ($45 per month) of the children’s noncovered medical expenses, and in failing to credit those amounts in determining his net income for calculating his child support obligation. In her brief, Jennifer Jarvis conceded Gene Jarvis’s health insurance obligation should only be $31.50 per month. We direct the judgment be so modified.
[¶ 10] In determining Gene Jarvis’s net monthly income of $1,227, for which the presumptively correct child support obligation for two children under the child support guidelines is $356 per month, the trial court deducted his obligations for Medicare, FICA, and income taxes from his gross income. The trial court did not deduct the portion of the health insurance premiums Gene Jarvis was paying to afford coverage for the children. N.D. Admin. Code § 75-02-04.1-01(7)(d) requires such payments be deducted in determining a child support obligor’s net income.
[¶ 11] Applying the proper deduction under N.D. Admin. Code § 75-02-04.1-01(7)(d) for a portion of the health insurance premiums does not, however, change Gene Jarvis’s child support obligation. Deducting the $31.50 per month conceded by Jennifer Jarvis to be the correct amount for his health insurance obligation results in a net monthly income of $1,195.50. Under N.D. Admin. Code § 75-02-04.1-02(5), “an obligor’s monthly net income amount ending in fifty dollars or more must be rounded up to the nearest one hundred dollars, and must otherwise be rounded down to the nearest one hundred dollars.” Thus, Gene Jarvis’s net monthly income must be rounded up to $1,200 per month, which, under N.D. Admin. Code § 75-02-04.1-10, results in a child support obligation of $356 per month for two children, which is his present obligation under the judgment.
[¶ 12] Regarding the requirement he pay one-half of the children’s medical expenses not covered by health insurance, Gene Jarvis argues the trial court did not explain or make sufficient findings to justify an upward deviation from the guidelines.
[¶ 13] Prior to the state adopting guidelines under the Family Support Act of 1988, child support awards were subject mainly to the discretion of the judge. See Laura W. Morgan, Child Support Guidelines: Interpretation and Application § 1.01 (1996). Generally, a judge would determine the monthly support award based on the needs of the child, and make a similar determination on the medical needs of the child. See, e.g., Nichols v. Tedder, 547 So.2d 766, 768-69 (Miss.1989) (stating “child support is but one type of expense which the court may award for the care and maintenance of children,” and that medical, dental, optical, and psychiatric expenses are other properly awarded expenses).
[¶ 14] In 1988, the federal government required the states to enact mandatory (“presumptively correct”) child support guidelines, in order to continue to receive federal funding of Aid to Families with Dependent Children (AFDC). Family Support Act of 1988, Pub.L. 100-485, codified primarily at 42 U.S.C. §§ 654, 666-67. The federal government also required the states to require provision for a “child[ren]’s health care needs, through health insurance coverage or other means.” See 45 C.F.R. § 302.56(c)(3).
[¶ 15] To comply with the federal requirements in the Budget Reconciliation Act of 1987 and the Family Support Act of 1988, North Dakota passed Senate Bill 2245 in 1989. Hearing on S.B. 22⅛,5 Before the House Human Services and Veterans Af*88fairs Comm., 51st N.D. Legis. Sess. (Mar. 10, 1989). The legislature’s bill summary of S.B. 2245 states:
Generally, this bill:
As amended, establishes provisions relating to the direct payment of child support payments to the clerk of court, rebut-table presumptions that a child support amount in compliance with support guidelines is the correct amount, immediate withholding of income for payment of child support, periodic review of child support orders and notice of the review results, health insurance coverage for a child who is the subject of a child support order; and genetic rather than blood test for purposes of determining paternity. The bill has varying effective dates for different sections of the bill.
Bill Summary of S.B. 22J5, 51st N.D. Legis. Sess. (Mar. 21,1989).
[¶ 16] The North Dakota child support statutes and guidelines do not contain specific references to uninsured medical expenses. However, other state courts have addressed the issue of uninsured medical expenses awarded in conjunction with a child support award. These state courts have found it within the trial court’s discretion to require, in addition to the child support award, payment of uninsured medical expenses. See generally Lulay v. Lulay, 588 N.E.2d 171, 172 (Ind.Ct.App.1991) (finding the commentary to the Child Support Guidelines allows for apportionment of uninsured medical expenses because the guidelines do not mandate any specific treatment of these expenses); Holdsworth v. Holdsworth, 621 So.2d 71, 78 and n. 1 (La.Ct.App.1993) (holding there was no error when medical expenses described by the trial court as “medical and dental expenses not covered by insurance” were apportioned half to each party, in addition to the child support award as determined under the guidelines); Jamison v. Jamison, 845 S.W.2d 133, 136-37 (Mo.Ct.App.1993) (holding it was within the court’s discretion to order the obligor to pay half of the uninsured medical expenses, in addition to the child support award . determined under the guidelines); Lawrence v. Tise, 107 N.C.App. 140, 419 S.E.2d 176, 183 (1992) (holding ordinary medical expenses not covered by insurance are to be apportioned between the parties at the discretion of the trial court, in addition to the child support award as determined by the guidelines). But see Hazuga v. Hazuga, 648 N.E.2d 391, 395 n. 1 (Ind.Ct.App.1995) (noting that the guidelines had been amended and therefore declined to follow Lulay v. Lulay), Division of Family Services ex rel. J.L.M. by C.A.M. v. Buttram, 924 S.W.2d 870, 871 (Mo.Ct.App.1996) (ordering father to pay 50 percent of all uncovered medical expenses was a deviation under the guidelines). These cases generally hold uninsured medical expenses are properly apportioned in conjunction with a child support award under their respective guidelines. The North Dakota guidelines are unique from all other states in their treatment of “medical expenses.” Morgan, supra, § 3.01[b][l] n. 21 (Supp.1998). Therefore, while other states may offer guidance on the issue, we must still determine the requirements under North Dakota law and its child support guidelines.
[¶ 17] The North Dakota Century Code addresses medical expenses with regard to child support at N.D.C.C. § 14-09-08.10, providing:1
1. Unless the obligee has comparable or better group dependent health insurance coverage available at no or nominal cost, the court shall order the obligor to name the minor child as beneficiary on any health insurance *89plan that is available to the obligor at no or nominal cost.
2. If the court finds that dependent health insurance is not available to the obligor or obligee at no or nominal cost, the court may require the obligor to obtain dependent health insurance, or to be liable for reasonable and necessary medical expenses of the child.
[¶ 18] Medical expenses can be separated into three categories: payments made for medical insurance for the child; payments made for uninsured medical expenses incurred, such as checkups or medication for the child; and any payments made for extraordinary medical expenses of the child. See Morgan, supra, § 3.01[b][3] n. 40 (Supp. 1998). Under the child support guidelines, North Dakota has addressed all three categories relating to medical expenses. The guidelines address health insurance, N.D. Admin. Code § 75-02-04.1-01(7)(d), uninsured expenses, see N.D. Admin. Code § 75-02-04.1-01(7)(e), and extraordinary expenses, see N.D. Admin. Code § 75-02-04.1-09(2)(d).
[¶ 19] N.D. Admin. Code § 75-02-04.1-01(7)(d) of the guidelines, dealing with medical insurance, provides:
7. “Net income” means total gross monthly income less:
d. A portion of premium payments, made by the person whose income is being determined, for health insurance policies or health service contracts, intended to afford coverage for the child or children for whom support is being sought, determined by dividing the payment by the total number of persons covered and multiplying the result times the number of such children.
This provision allows for a deduction from the obligor’s net income of premiums paid for medical insurance for a child subject to the support order. Shipley v. Shipley, 509 N.W.2d 49, 53 (N.D.1993).
[¶ 20] Next, N.D. Admin. Code § 75-02-04.1-01(7)(e) of the guidelines, dealing with medical expenses, provides:
7. “Net income” means total gross monthly income less:
e. Payments made on actual medical expenses of the child or children for whom support is being sought.
This provision allows the obligor to deduct from gross income any actual medical expenses paid for a child subject to the support award. Withey v. Hager, 1997 ND 225, ¶ 9, 571 N.W.2d 142.
[¶21] And finally, N.D. Admin. Code § 75 — 02—04.1—09(2)(d) of the guidelines, dealing with extraordinary expenses, provides:
2. The presumption that the amount of child support that would result from the application of this chapter, except for this subsection, is the correct amount of child support is rebutted only if a preponderance of the evidence establishes that a deviation from the guidelines is in the best interest of the supported children and:
d. The increased needs of children with disabling conditions or chronic illness.
This section allows a deviation from the presumptively correct child support amount for the “increased needs” of a child with a disabling condition or chronic illness.
[¶ 22] The guidelines do not contain a specific reference to uninsured medical costs, but “rules have the force and effect of law.” N.D.C.C. § 28-32-03(3). “Therefore, ‘we rely upon the principles of statutory construction when interpreting administrative rules and regulations.’ ” Perala v. Carlson, 520 N.W.2d 839, 842 (N.D.1994) (quoting Madler v. McKenzie County, 496 N.W.2d 17, 21 (N.D.1993)). Words are to be used and understood in their ordinary sense. N.D.C.C. § 1-02-02. When “increased needs” is compared with “medical expenses,” as used in the guidelines, it is obvious “increased needs” connotes the extraordinary or unexpected, whereas “medical expenses” implies all regular costs associated with providing health care to the child. See generally Morgan, supra, § 3.01[b][3] and n. 40 (Supp.1998).
[¶ 23] The North Dakota guidelines expressly allow the obligor to deduct from his net income any insurance premiums and any actual medical expenses paid. N.D. Ad*90min. Code § 75-02-04.1-01(7)(d) and (e). Furthermore, the Department of Human Services has provided an exclusive listing of factors available to rebut the presumptively correct amount of child support. Horner v. Horner, 549 N.W.2d 669, 670 (N.D.1996). This exclusive listing includes “the increased needs of children with disabling conditions or chronic illness,” but makes no mention of medical insurance premiums or uninsured medical expenses. N.D. Admin. Code § 75-02 — 04.1—09(2)(d). This is because the guidelines treat medical insurance premiums and any other actual medical expenses, such as uninsured medical expenses, as not being included in the child support award. Hence they are deductions from gross income, and not criteria for rebuttal of a guideline child support amount.
[¶ 24] To treat uninsured medical expenses as included in the presumptively correct child support amount would produce an anomalous and unjust result. Under the guidelines, the expenses are to be treated as a deduction from gross income, thereby reducing the amount of child support to be received. N.D. Admin. Code § 75 — 02—04.1—01(7)(e). Yet, if we were to accept Gene Jarvis’s argument that uninsured expenses are included in the presumptively correct amount of support, it would produce a situation in which the expenses are used to reduce the obligor’s child support income and at the same time are also considered part of child support itself, thereby further reducing the child support award. Put simply, Gene Jarvis seeks double credit for the uninsured medical expenses he pays.
[¶ 25] In light of the historical definition of child support, the treatment of uninsured medical expenses by other state courts, and the treatment of uninsured medical expenses by the North Dakota child support guidelines, it is apparent N.D.C.C. § 14-09-08.10 authorizes the award of uninsured medical expenses in conjunction with the child support award. This avoids the anomalous effects mentioned and properly aligns North Dakota law with the state and federal government’s intent of providing for the health care needs of children. See, e.g., N.D.C.C. §§ 14-09-08.11 to 14-09-08.15; 45 C.F.R. § 302.56(e)(3). To the extent Dickson v. Dickson, 1997 ND 167, 568 N.W.2d 284, is inconsistent with this holding, it is overruled.
[¶ 26] In denying the new trial motion, the trial court found the requirement that the obligor pay half of the uninsured medical expenses appropriate and within the law. We conclude the trial court did not abuse its discretion in this regard. Because the uninsured medical expenses will not reduce the obligor’s net income to a level that changes the awarded child support we need not remand for a redetermination of net income.2
IV
[¶ 27] Gene Jarvis contends the trial court erred in determining his obligations for child support, daycare, medical expenses, medical insurance, and preschool expenses without making specific findings supporting a devia-. tion from the guideline amount and without balancing the children’s needs with his ability to pay.
[¶ 28] Gene Jarvis agreed to pay one-half of his youngest daughter’s preschool tuition of $567 which Jennifer Jarvis had already paid with a loan from her father. We have already determined the child support obligation ordered by the trial court is the proper amount, based on Gene Jarvis’s net income as determined after taking the appropriate deductions from his gross income.
[¶ 29] The trial court ordered Gene Jarvis to pay one-half of the children’s daycare cost of $480 per month, in addition to child support of $356 per month. “N.D.C.C. § 14-09-09.7(3) creates a rebuttable presumption the amount calculated under the child support guidelines is the correct amount of support.” Harty v. Harty, 1998 ND 99, ¶ 14, 578 N.W.2d 519. The cost of a child’s daycare may justify an upward deviation from the guidelines’ presumptively correct support amount. Reinecke v. Griffeth, 533 N.W.2d 695, 701 (N.D.1995) (citing Pera*91la, 520 N.W.2d at 841). If a trial court considers the best interests of the children and deviates from the guideline amount of child support, it must make specific findings demonstrating why the guideline amount has been rebutted. Id. at 700-01. “[Findings are adequate if we are able to understand from them the factual basis for the trial court’s determination.” Wolf v. Wolf, 474 N.W.2d 257, 258 (N.D.1991). “[W]e have relied on implied findings of fact when the record has enabled us to understand ‘the factual determination made by the trial court and the basis for its conclusions of law and judgment entered thereon.’” Reinecke, at 698 (quoting All Seasons Water Users v. Northern Improvement Co., 399 N.W.2d 278, 281 (N.D.1987)).
[¶ 30] Jennifer Jarvis is working full time, netting approximately $975 per month, and incurring daycare expenses of $480 per month. In light of the parties’ incomes, it is clearly in the children’s best interests that Jennifer Jarvis continue working, and it is apparent she cannot, even with the required child support, afford the full cost of the children’s daycare expenses. “The court did not use the magic words ‘the guidelines are hereby rebutted,’ but the effect of its finding is the same: the increased child care expense resulting from [Andrea’s] preschool age and [Jennifer Jarvis’s] full-time employment requires an increase in [Gene Jarvis’s] support obligation from the presumptive amount.” Pernio, 520 N.W.2d at 843. Therefore, we conclude the trial court properly determined that the presumptive amount of child support under the guidelines was rebutted by the full cost of Andrea’s child care. We further conclude no productive purpose would be served by remanding for additional findings on this matter.
[¶ 31] Gene Jarvis contends the trial court deviated from the guideline amount of child support without considering his ability to pay in light of his needs to pay for healthcare, attorney fees,3 housing, food, and other necessities. The current child support guidelines prohibit a court from considering an obligor’s daily living expenses when setting child support. Horner, 549 N.W.2d at 670. Gene Jarvis has not shown any relevant ground upon which to base a downward deviation from the presumptive amount of child support under N.D. Admin. Code § 75-02-04.1-09. In denying the motion for a new trial, the trial court explained:
Gene’s net monthly income is $1,227. (Finding # 28). Until the parties’ separation, Gene also worked part-time at a second job earning over $3,000 per year, (Finding # 13)....
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Gene is capable of earning additional income. He voluntarily quit his part-time job the week the parties separated. All these obligations imposed by the Court on Gene are expenses on behalf of his children. Gene is fully capable of providing and contributing these expenses.
We are not persuaded the trial court failed to consider Gene Jarvis’s ability to pay the amounts ordered to the extent permissible under the guidelines.
V
[¶ 32] Gene Jarvis contends the trial court has deprived him of his rights under the Fifth Amendment to the United States Constitution by depriving him of life, liberty, and property without due process of law. He argues his “ability to live freely and with liberty is being curtailed by the trial court by the oppressive amounts of money he is being ordered to pay” and “[e]nforcement of this court’s order would deprive Gene Jarvis of significant property interests and his right to have enough income to feed, clothe, and shelter himself.”
[¶ 33] Gene Jarvis has cited only Bolling v. Sharpe, 347 U.S. 497, 499, 74 S.Ct. 693, 98 L.Ed. 884 (1954), for the proposition that liberty is not confined to freedom from bodily restraint but extends to the full range of conduct an individual is free to pursue, and Federal Deposit Ins. Corp. v. Morrison, 747 F.2d 610 (11th Cir.1984), for the proposition *92that the Due Process Clause of the Fifth Amendment extends protection to property rights less substantial than full legal title. Those are unassailable propositions that do not, however, support Gene Jarvis’s ultimate conclusion. He has provided neither persuasive authority, nor persuasive reasoning. Without more, his perfunctory constitutional argument is without merit, and we will not further address it. Parties mounting constitutional challenges should bring up the heavy artillery or forego the attack entirely. Trollwood Village Ltd. Partnership v. Cass County Bd. of County Comm’rs, 557 N.W.2d 732, 736 n. 5 (N.D.1996); Southern Valley Grain Dealers Ass’n v. Board of County Comm’rs of Richland County, 257 N.W.2d 425, 434 (N.D.1977).
YI
[¶ 34] Gene Jarvis contends the trial court erred in granting physical custody of the children to Jennifer Jarvis, rather than granting joint physical custody to both parties. He testified the children “should see both parents half the time and also live with the parents half the time” and proposed that he “would have the children half the time and pay one half the expenses.”
[¶ 35] “[S]plit or alternating custody is not per se erroneous.” Kaloupek v. Burfening, 440 N.W.2d 496, 497 (N.D.1989). However, to support an alternating custody arrangement, we require a factual finding it is in the child’s best interest, “because it is generally not in the child’s best interest to be bandied back and forth between parents in a rotating physical custody arrangement.” Kasprowicz v. Kasprowicz, 1998 ND 68, ¶ 15, 575 N.W.2d 921.
[¶36] “Legal writers and child development professionals are in general agreement that a joint custody arrangement can work only if the parents are able to cooperate.” 2 John P. McCahey et al., Child Custody & Visitation Law and Practice § 13.01 [1] (1998). “The success of any custody resolution must ultimately rest with the parents. If they cannot set aside their differences and conflict[s] when dealing with their roles as parents, the innocent child will most surely suffer.” Kaloupek, 440 N.W.2d at 499.
[¶ 37] In denying Gene Jarvis’s motion for a new trial, the trial court said, “Jennifer is definitely the primary caretaker.” The court noted its “expressed concern regarding Gene’s anger and hostility toward Jennifer,” and further explained: “Under these circumstances, splitting custody and authority over decisions affecting the children could only continue the animosity between the parties. It is in the children's best interest that they be in the custody of Jennifer and that Gene spend regular quality time with them.” In light of Jennifer Jarvis’s testimony indicating Gene Jarvis is “very angry that I’m in the house and he’s not in the house;” she and Gene Jarvis communicate “[v]ery little;” and they “would need to communicate a lot” with a joint physical custody arrangement, we conclude the trial court did not abuse its discretion by denying the motion for a new trial on this matter.
VII
[¶ 38] We direct the judgment be modified to require Gene Jarvis to pay $31.50 per month toward the children’s health insurance premiums. With the judgment so modified, we affirm the trial court’s order denying Gene Jarvis’s post-trial motions.
[¶ 39] MARING and MESCHKE, JJ., concur.. Section 14-09-08.10, N.D.C.C., was amended subsequent to this action. In its amended form, it provides:
Order. Each order entered under this code for the support of a minor child must include a provision for health insurance coverage for that child.
1. Except as provided in subsection 2, the order must require the obligor to provide satisfactory health insurance coverage whenever that coverage is available at reasonable cost or becomes available at reasonable cost. 2. If the obligee is an individual with physical custody of the child, the obligee must be required to provide satisfactory health insurance whenever that coverage is available at no or nominal cost.
1997 N.D. Sess. Laws ch. 404, § 17.
. The obligor’s current net income is $1,195.50. After we subtract the monthly uninsured expenses of $45, the net income is $1,150.50. Under the guidelines, we must round to the nearest hundred dollars, which would be $1,200. N.D. Admin. Code § 75-02-04.1-02(5). This is the same net income used to determine his current child support obligation.
. Gene Jarvis alleged in his brief he is paying attorney fees of $262 per month. He testified at trial he had no unpaid attorney fees at that time.