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	$137.83	10.756%	$152.655	$152.66	$152.65	$152.70
Purchase #2	$152.60	12.793%	$172.1221	$172.12	$172.10	$172.10
Purchase #3	$215.80	5.295%	$227.2266	$227.23	$227.25	$227.20
Purchase #4	$78.74	8.601%	$85.5124	$85.51	$85.50	$85.50
Purchase #5	$138.62	8.474%	$150.3667	$150.37	$150.35	$150.40
Purchase #6	$203.53	5.548%	$214.8218	$214.82	$214.80	$214.80
Purchase #7	$49.31	6.271%	$52.4022	$52.40	$52.40	$52.40
7 purchase totals =	$976.43		$1,055.1068	$1,055.11	$1,055.05	$1,055.10