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	$215.75	7.250%	$231.3919	$231.39	$231.40	$231.40
Purchase #2	$32.92	10.853%	$36.4928	$36.49	$36.50	$36.50
Purchase #3	$205.75	8.237%	$222.6976	$222.70	$222.70	$222.70
Purchase #4	$108.56	11.584%	$121.1356	$121.14	$121.15	$121.10
Purchase #5	$225.65	13.760%	$256.6994	$256.70	$256.70	$256.70
Purchase #6	$240.96	9.668%	$264.256	$264.26	$264.25	$264.30
Purchase #7	$84.81	5.367%	$89.3618	$89.36	$89.35	$89.40
7 purchase totals =	$1,114.40		$1,222.0351	$1,222.04	$1,222.05	$1,222.10