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	$184.51	11.264%	$205.2932	$205.29	$205.30	$205.30
Purchase #2	$111.53	6.162%	$118.4025	$118.40	$118.40	$118.40
Purchase #3	$13.85	4.470%	$14.4691	$14.47	$14.45	$14.50
Purchase #4	$75.58	13.185%	$85.5452	$85.55	$85.55	$85.50
Purchase #5	$180.95	12.846%	$204.1948	$204.19	$204.20	$204.20
Purchase #6	$146.90	13.174%	$166.2526	$166.25	$166.25	$166.30
Purchase #7	$235.31	8.565%	$255.4643	$255.46	$255.45	$255.50
7 purchase totals =	$948.63		$1,049.6217	$1,049.61	$1,049.60	$1,049.70