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	$185.72	5.244%	$195.4592	$195.46	$195.45	$195.50
Purchase #2	$10.40	13.712%	$11.826	$11.83	$11.85	$11.80
Purchase #3	$96.51	8.497%	$104.7105	$104.71	$104.70	$104.70
Purchase #4	$239.87	11.655%	$267.8268	$267.83	$267.85	$267.80
Purchase #5	$156.58	6.441%	$166.6653	$166.67	$166.65	$166.70
Purchase #6	$153.71	7.679%	$165.5134	$165.51	$165.50	$165.50
Purchase #7	$174.68	5.505%	$184.2961	$184.30	$184.30	$184.30
7 purchase totals =	$1,017.47		$1,096.2973	$1,096.31	$1,096.30	$1,096.30