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	$200.47	4.775%	$210.0424	$210.04	$210.05	$210.00
Purchase #2	$128.30	6.581%	$136.7434	$136.74	$136.75	$136.70
Purchase #3	$137.32	11.344%	$152.8976	$152.90	$152.90	$152.90
Purchase #4	$99.32	6.376%	$105.6526	$105.65	$105.65	$105.70
Purchase #5	$93.95	12.770%	$105.9474	$105.95	$105.95	$105.90
Purchase #6	$197.57	8.576%	$214.5136	$214.51	$214.50	$214.50
Purchase #7	$92.62	7.422%	$99.4943	$99.49	$99.50	$99.50
7 purchase totals =	$949.55		$1,025.2913	$1,025.28	$1,025.30	$1,025.20