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	$56.40	11.137%	$62.6813	$62.68	$62.70	$62.70
Purchase #2	$77.50	7.213%	$83.0901	$83.09	$83.10	$83.10
Purchase #3	$151.35	9.590%	$165.8645	$165.86	$165.85	$165.90
Purchase #4	$79.76	10.444%	$88.0901	$88.09	$88.10	$88.10
Purchase #5	$223.63	9.323%	$244.479	$244.48	$244.50	$244.50
Purchase #6	$139.71	6.551%	$148.8624	$148.86	$148.85	$148.90
Purchase #7	$135.82	3.420%	$140.465	$140.47	$140.45	$140.50
7 purchase totals =	$864.17		$933.5324	$933.53	$933.55	$933.70