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	$211.46	6.845%	$225.9344	$225.93	$225.95	$225.90
Purchase #2	$6.86	10.482%	$7.5791	$7.58	$7.60	$7.60
Purchase #3	$225.95	7.427%	$242.7313	$242.73	$242.75	$242.70
Purchase #4	$242.72	13.196%	$274.7493	$274.75	$274.75	$274.70
Purchase #5	$174.49	9.194%	$190.5326	$190.53	$190.55	$190.50
Purchase #6	$108.77	3.261%	$112.317	$112.32	$112.30	$112.30
Purchase #7	$172.53	3.846%	$179.1655	$179.17	$179.15	$179.20
7 purchase totals =	$1,142.78		$1,233.0092	$1,233.01	$1,233.05	$1,232.90