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	$61.92	9.208%	$67.6216	$67.62	$67.60	$67.60
Purchase #2	$13.70	5.671%	$14.4769	$14.48	$14.50	$14.50
Purchase #3	$42.78	6.519%	$45.5688	$45.57	$45.55	$45.60
Purchase #4	$20.25	5.490%	$21.3617	$21.36	$21.35	$21.40
Purchase #5	$111.64	11.513%	$124.4931	$124.49	$124.50	$124.50
Purchase #6	$138.52	12.252%	$155.4915	$155.49	$155.50	$155.50
Purchase #7	$7.68	11.667%	$8.576	$8.58	$8.60	$8.60
7 purchase totals =	$396.49		$437.5896	$437.59	$437.60	$437.70