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	$66.94	7.491%	$71.9545	$71.95	$71.95	$72.00
Purchase #2	$211.45	9.485%	$231.506	$231.51	$231.50	$231.50
Purchase #3	$140.67	7.733%	$151.548	$151.55	$151.55	$151.50
Purchase #4	$41.59	3.196%	$42.9192	$42.92	$42.90	$42.90
Purchase #5	$156.71	10.793%	$173.6237	$173.62	$173.60	$173.60
Purchase #6	$245.36	13.178%	$277.6935	$277.69	$277.70	$277.70
Purchase #7	$132.79	12.713%	$149.6716	$149.67	$149.65	$149.70
7 purchase totals =	$995.51		$1,098.9165	$1,098.91	$1,098.85	$1,098.90