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	$53.86	12.197%	$60.4293	$60.43	$60.45	$60.40
Purchase #2	$12.90	3.844%	$13.3959	$13.40	$13.40	$13.40
Purchase #3	$248.25	6.104%	$263.4032	$263.40	$263.40	$263.40
Purchase #4	$243.65	10.622%	$269.5305	$269.53	$269.55	$269.50
Purchase #5	$134.98	13.146%	$152.7245	$152.72	$152.70	$152.70
Purchase #6	$220.98	5.863%	$233.9361	$233.94	$233.95	$233.90
Purchase #7	$41.94	3.589%	$43.4452	$43.45	$43.45	$43.40
7 purchase totals =	$956.56		$1,036.8647	$1,036.87	$1,036.90	$1,036.70