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	$84.72	12.338%	$95.1728	$95.17	$95.15	$95.20
Purchase #2	$38.78	3.508%	$40.1404	$40.14	$40.15	$40.10
Purchase #3	$19.74	13.413%	$22.3877	$22.39	$22.40	$22.40
Purchase #4	$196.44	11.425%	$218.8833	$218.88	$218.90	$218.90
Purchase #5	$234.78	5.425%	$247.5168	$247.52	$247.50	$247.50
Purchase #6	$126.54	13.302%	$143.3724	$143.37	$143.35	$143.40
Purchase #7	$236.32	9.223%	$258.1158	$258.12	$258.10	$258.10
7 purchase totals =	$937.32		$1,025.5892	$1,025.59	$1,025.55	$1,025.60