Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$167.38	8.829%	$182.158	$182.16	$182.15	$182.20
Purchase #2	$66.93	4.434%	$69.8977	$69.90	$69.90	$69.90
Purchase #3	$165.52	6.531%	$176.3301	$176.33	$176.35	$176.30
Purchase #4	$93.93	5.568%	$99.16	$99.16	$99.15	$99.20
Purchase #5	$134.75	10.109%	$148.3719	$148.37	$148.35	$148.40
Purchase #6	$121.52	13.412%	$137.8183	$137.82	$137.80	$137.80
Purchase #7	$10.32	9.712%	$11.3223	$11.32	$11.30	$11.30
7 purchase totals =	$760.35		$825.0583	$825.06	$825.00	$825.10