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	$185.88	5.300%	$195.7316	$195.73	$195.75	$195.70
Purchase #2	$212.31	10.530%	$234.6662	$234.67	$234.65	$234.70
Purchase #3	$159.30	8.130%	$172.2511	$172.25	$172.25	$172.30
Purchase #4	$222.25	12.688%	$250.4491	$250.45	$250.45	$250.40
Purchase #5	$77.36	11.342%	$86.1342	$86.13	$86.15	$86.10
Purchase #6	$104.34	11.583%	$116.4257	$116.43	$116.45	$116.40
Purchase #7	$133.69	12.309%	$150.1459	$150.15	$150.15	$150.10
7 purchase totals =	$1,095.13		$1,205.8038	$1,205.81	$1,205.85	$1,205.70