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	$147.64	7.485%	$158.6909	$158.69	$158.70	$158.70
Purchase #2	$248.56	4.662%	$260.1479	$260.15	$260.15	$260.10
Purchase #3	$20.67	4.699%	$21.6413	$21.64	$21.65	$21.60
Purchase #4	$101.57	9.742%	$111.4649	$111.46	$111.45	$111.50
Purchase #5	$219.35	13.629%	$249.2452	$249.25	$249.25	$249.20
Purchase #6	$57.68	13.766%	$65.6202	$65.62	$65.60	$65.60
Purchase #7	$188.65	9.649%	$206.8528	$206.85	$206.85	$206.90
7 purchase totals =	$984.12		$1,073.6632	$1,073.66	$1,073.65	$1,073.60