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	$61.40	6.795%	$65.5721	$65.57	$65.55	$65.60
Purchase #2	$62.31	6.724%	$66.4997	$66.50	$66.50	$66.50
Purchase #3	$242.38	6.608%	$258.3965	$258.40	$258.40	$258.40
Purchase #4	$195.95	8.301%	$212.2158	$212.22	$212.20	$212.20
Purchase #5	$166.34	11.208%	$184.9834	$184.98	$185.00	$185.00
Purchase #6	$137.57	10.429%	$151.9172	$151.92	$151.90	$151.90
Purchase #7	$195.78	8.502%	$212.4252	$212.43	$212.45	$212.40
7 purchase totals =	$1,061.73		$1,152.0099	$1,152.02	$1,152.00	$1,152.00