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	$149.61	13.188%	$169.3406	$169.34	$169.35	$169.30
Purchase #2	$9.69	13.261%	$10.975	$10.98	$11.00	$11.00
Purchase #3	$244.98	8.278%	$265.2594	$265.26	$265.25	$265.30
Purchase #4	$205.82	9.577%	$225.5314	$225.53	$225.55	$225.50
Purchase #5	$139.98	9.333%	$153.0443	$153.04	$153.05	$153.00
Purchase #6	$233.58	3.753%	$242.3463	$242.35	$242.35	$242.30
Purchase #7	$76.90	11.129%	$85.4582	$85.46	$85.45	$85.50
7 purchase totals =	$1,060.56		$1,151.9552	$1,151.96	$1,152.00	$1,151.90