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	$91.75	4.212%	$95.6145	$95.61	$95.60	$95.60
Purchase #2	$10.85	4.402%	$11.3276	$11.33	$11.35	$11.30
Purchase #3	$247.44	11.230%	$275.2275	$275.23	$275.25	$275.20
Purchase #4	$158.80	13.715%	$180.5794	$180.58	$180.60	$180.60
Purchase #5	$248.52	11.721%	$277.649	$277.65	$277.65	$277.60
Purchase #6	$154.25	3.136%	$159.0873	$159.09	$159.10	$159.10
Purchase #7	$16.34	13.464%	$18.54	$18.54	$18.55	$18.50
7 purchase totals =	$927.95		$1,018.0253	$1,018.03	$1,018.10	$1,017.90