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	$191.95	11.855%	$214.7057	$214.71	$214.70	$214.70
Purchase #2	$6.89	9.461%	$7.5419	$7.54	$7.55	$7.50
Purchase #3	$31.89	13.381%	$36.1572	$36.16	$36.15	$36.20
Purchase #4	$49.80	7.250%	$53.4105	$53.41	$53.40	$53.40
Purchase #5	$10.77	5.183%	$11.3282	$11.33	$11.35	$11.30
Purchase #6	$132.37	13.523%	$150.2704	$150.27	$150.25	$150.30
Purchase #7	$125.90	9.282%	$137.586	$137.59	$137.60	$137.60
7 purchase totals =	$549.57		$610.9999	$611.01	$611.00	$611.00