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	$200.65	12.264%	$225.2577	$225.26	$225.25	$225.30
Purchase #2	$183.31	6.769%	$195.7183	$195.72	$195.70	$195.70
Purchase #3	$36.68	11.114%	$40.7566	$40.76	$40.75	$40.80
Purchase #4	$249.87	5.359%	$263.2605	$263.26	$263.25	$263.30
Purchase #5	$172.52	10.644%	$190.883	$190.88	$190.90	$190.90
Purchase #6	$170.77	8.389%	$185.0959	$185.10	$185.10	$185.10
Purchase #7	$231.51	13.377%	$262.4791	$262.48	$262.50	$262.50
7 purchase totals =	$1,245.31		$1,363.4511	$1,363.46	$1,363.45	$1,363.60