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	$114.38	3.725%	$118.6407	$118.64	$118.65	$118.60
Purchase #2	$49.37	4.118%	$51.4031	$51.40	$51.40	$51.40
Purchase #3	$13.32	8.572%	$14.4618	$14.46	$14.45	$14.50
Purchase #4	$49.88	4.715%	$52.2318	$52.23	$52.25	$52.20
Purchase #5	$126.41	10.605%	$139.8158	$139.82	$139.80	$139.80
Purchase #6	$143.53	5.797%	$151.8504	$151.85	$151.85	$151.90
Purchase #7	$179.50	6.555%	$191.2662	$191.27	$191.25	$191.30
7 purchase totals =	$676.39		$719.6698	$719.67	$719.65	$719.70