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	$148.83	8.272%	$161.1412	$161.14	$161.15	$161.10
Purchase #2	$204.45	10.130%	$225.1608	$225.16	$225.15	$225.20
Purchase #3	$136.34	5.183%	$143.4065	$143.41	$143.40	$143.40
Purchase #4	$248.65	3.319%	$256.9027	$256.90	$256.90	$256.90
Purchase #5	$67.33	10.500%	$74.3997	$74.40	$74.40	$74.40
Purchase #6	$130.81	13.605%	$148.6067	$148.61	$148.60	$148.60
Purchase #7	$32.50	4.320%	$33.904	$33.90	$33.90	$33.90
7 purchase totals =	$968.91		$1,043.5216	$1,043.52	$1,043.50	$1,043.50