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	$119.70	10.244%	$131.9621	$131.96	$131.95	$132.00
Purchase #2	$67.62	7.381%	$72.611	$72.61	$72.60	$72.60
Purchase #3	$18.82	4.696%	$19.7038	$19.70	$19.70	$19.70
Purchase #4	$226.37	13.444%	$256.8032	$256.80	$256.80	$256.80
Purchase #5	$95.85	4.567%	$100.2275	$100.23	$100.25	$100.20
Purchase #6	$103.55	7.624%	$111.4447	$111.44	$111.45	$111.40
Purchase #7	$50.25	10.791%	$55.6725	$55.67	$55.65	$55.70
7 purchase totals =	$682.16		$748.4248	$748.41	$748.40	$748.40