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	$215.45	4.459%	$225.0569	$225.06	$225.05	$225.10
Purchase #2	$183.73	13.601%	$208.7191	$208.72	$208.70	$208.70
Purchase #3	$148.88	11.430%	$165.897	$165.90	$165.90	$165.90
Purchase #4	$33.40	11.273%	$37.1652	$37.17	$37.15	$37.20
Purchase #5	$13.35	13.584%	$15.1635	$15.16	$15.15	$15.20
Purchase #6	$233.92	8.859%	$254.643	$254.64	$254.65	$254.60
Purchase #7	$212.81	10.393%	$234.9273	$234.93	$234.95	$234.90
7 purchase totals =	$1,041.54		$1,141.5720	$1,141.58	$1,141.55	$1,141.60