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	$39.87	9.496%	$43.6561	$43.66	$43.65	$43.70
Purchase #2	$17.83	3.653%	$18.4813	$18.48	$18.50	$18.50
Purchase #3	$65.49	7.653%	$70.5019	$70.50	$70.50	$70.50
Purchase #4	$100.73	10.604%	$111.4114	$111.41	$111.40	$111.40
Purchase #5	$67.42	6.312%	$71.6756	$71.68	$71.70	$71.70
Purchase #6	$111.58	6.733%	$119.0927	$119.09	$119.10	$119.10
Purchase #7	$25.91	8.853%	$28.2038	$28.20	$28.20	$28.20
7 purchase totals =	$428.83		$463.0228	$463.02	$463.05	$463.10