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	$141.65	5.188%	$148.9988	$149.00	$149.00	$149.00
Purchase #2	$107.54	10.810%	$119.1651	$119.17	$119.15	$119.20
Purchase #3	$140.53	8.525%	$152.5102	$152.51	$152.50	$152.50
Purchase #4	$141.90	13.327%	$160.811	$160.81	$160.80	$160.80
Purchase #5	$58.63	7.240%	$62.8748	$62.87	$62.85	$62.90
Purchase #6	$214.67	7.546%	$230.869	$230.87	$230.85	$230.90
Purchase #7	$166.76	11.133%	$185.3254	$185.33	$185.35	$185.30
7 purchase totals =	$971.68		$1,060.5543	$1,060.56	$1,060.50	$1,060.60