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	$93.45	13.725%	$106.276	$106.28	$106.30	$106.30
Purchase #2	$212.28	8.575%	$230.483	$230.48	$230.50	$230.50
Purchase #3	$83.70	10.103%	$92.1562	$92.16	$92.15	$92.20
Purchase #4	$143.86	10.396%	$158.8157	$158.82	$158.80	$158.80
Purchase #5	$134.45	7.120%	$144.0228	$144.02	$144.00	$144.00
Purchase #6	$169.53	12.632%	$190.945	$190.95	$190.95	$190.90
Purchase #7	$196.38	6.727%	$209.5905	$209.59	$209.60	$209.60
7 purchase totals =	$1,033.65		$1,132.2892	$1,132.30	$1,132.30	$1,132.30