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	$9.54	12.137%	$10.6979	$10.70	$10.70	$10.70
Purchase #2	$37.71	7.463%	$40.5243	$40.52	$40.50	$40.50
Purchase #3	$88.42	5.663%	$93.4272	$93.43	$93.45	$93.40
Purchase #4	$159.45	3.367%	$164.8187	$164.82	$164.80	$164.80
Purchase #5	$235.41	5.683%	$248.7884	$248.79	$248.80	$248.80
Purchase #6	$238.96	7.388%	$256.6144	$256.61	$256.60	$256.60
Purchase #7	$103.40	12.620%	$116.4491	$116.45	$116.45	$116.40
7 purchase totals =	$872.89		$931.3200	$931.32	$931.30	$931.20