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	$92.69	6.197%	$98.434	$98.43	$98.45	$98.40
Purchase #2	$11.47	8.722%	$12.4704	$12.47	$12.45	$12.50
Purchase #3	$222.60	13.655%	$252.996	$253.00	$253.00	$253.00
Purchase #4	$247.58	11.334%	$275.6407	$275.64	$275.65	$275.60
Purchase #5	$231.28	9.606%	$253.4968	$253.50	$253.50	$253.50
Purchase #6	$28.29	13.759%	$32.1824	$32.18	$32.20	$32.20
Purchase #7	$185.52	12.433%	$208.5857	$208.59	$208.60	$208.60
7 purchase totals =	$1,019.43		$1,133.8060	$1,133.81	$1,133.85	$1,133.80