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	$212.82	3.621%	$220.5262	$220.53	$220.55	$220.50
Purchase #2	$37.45	8.156%	$40.5044	$40.50	$40.50	$40.50
Purchase #3	$145.91	3.771%	$151.4123	$151.41	$151.40	$151.40
Purchase #4	$189.95	12.733%	$214.1363	$214.14	$214.15	$214.10
Purchase #5	$143.70	10.225%	$158.3933	$158.39	$158.40	$158.40
Purchase #6	$139.62	8.623%	$151.6594	$151.66	$151.65	$151.70
Purchase #7	$113.77	11.215%	$126.5293	$126.53	$126.55	$126.50
7 purchase totals =	$983.22		$1,063.1612	$1,063.16	$1,063.20	$1,063.10