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	$87.40	8.327%	$94.6778	$94.68	$94.70	$94.70
Purchase #2	$154.37	11.419%	$171.9975	$172.00	$172.00	$172.00
Purchase #3	$129.83	11.240%	$144.4229	$144.42	$144.40	$144.40
Purchase #4	$203.91	4.243%	$212.5619	$212.56	$212.55	$212.60
Purchase #5	$160.61	7.107%	$172.0246	$172.02	$172.00	$172.00
Purchase #6	$157.61	6.738%	$168.2298	$168.23	$168.25	$168.20
Purchase #7	$61.40	11.679%	$68.5709	$68.57	$68.55	$68.60
7 purchase totals =	$955.13		$1,032.4854	$1,032.48	$1,032.45	$1,032.50