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	$208.27	4.121%	$216.8528	$216.85	$216.85	$216.90
Purchase #2	$141.40	7.587%	$152.128	$152.13	$152.15	$152.10
Purchase #3	$239.77	8.473%	$260.0857	$260.09	$260.10	$260.10
Purchase #4	$159.90	7.688%	$172.1931	$172.19	$172.20	$172.20
Purchase #5	$206.44	11.584%	$230.354	$230.35	$230.35	$230.40
Purchase #6	$81.45	4.488%	$85.1055	$85.11	$85.10	$85.10
Purchase #7	$41.39	10.321%	$45.6619	$45.66	$45.65	$45.70
7 purchase totals =	$1,078.62		$1,162.3810	$1,162.38	$1,162.40	$1,162.50