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	$88.54	7.464%	$95.1486	$95.15	$95.15	$95.10
Purchase #2	$40.34	4.587%	$42.1904	$42.19	$42.20	$42.20
Purchase #3	$25.66	3.256%	$26.4955	$26.50	$26.50	$26.50
Purchase #4	$67.66	4.733%	$70.8623	$70.86	$70.85	$70.90
Purchase #5	$154.81	11.471%	$172.5683	$172.57	$172.55	$172.60
Purchase #6	$110.89	4.708%	$116.1107	$116.11	$116.10	$116.10
Purchase #7	$214.53	12.779%	$241.9448	$241.94	$241.95	$241.90
7 purchase totals =	$702.43		$765.3206	$765.32	$765.30	$765.30