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	$190.71	3.218%	$196.847	$196.85	$196.85	$196.80
Purchase #2	$65.31	10.499%	$72.1669	$72.17	$72.15	$72.20
Purchase #3	$232.47	6.543%	$247.6805	$247.68	$247.70	$247.70
Purchase #4	$147.46	5.600%	$155.7178	$155.72	$155.70	$155.70
Purchase #5	$48.48	8.726%	$52.7104	$52.71	$52.70	$52.70
Purchase #6	$143.86	9.816%	$157.9813	$157.98	$158.00	$158.00
Purchase #7	$91.39	8.371%	$99.0403	$99.04	$99.05	$99.00
7 purchase totals =	$919.68		$982.1442	$982.15	$982.15	$982.10