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	$175.90	10.635%	$194.607	$194.61	$194.60	$194.60
Purchase #2	$235.65	8.472%	$255.6143	$255.61	$255.60	$255.60
Purchase #3	$131.67	9.747%	$144.5039	$144.50	$144.50	$144.50
Purchase #4	$153.37	12.499%	$172.5397	$172.54	$172.55	$172.50
Purchase #5	$189.26	8.726%	$205.7748	$205.77	$205.75	$205.80
Purchase #6	$12.65	11.756%	$14.1371	$14.14	$14.15	$14.10
Purchase #7	$76.47	10.154%	$84.2348	$84.23	$84.25	$84.20
7 purchase totals =	$974.97		$1,071.4116	$1,071.40	$1,071.40	$1,071.30