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	$133.65	11.373%	$148.85	$148.85	$148.85	$148.90
Purchase #2	$228.97	6.680%	$244.2652	$244.27	$244.25	$244.30
Purchase #3	$177.31	7.616%	$190.8139	$190.81	$190.80	$190.80
Purchase #4	$75.40	10.307%	$83.1715	$83.17	$83.15	$83.20
Purchase #5	$129.68	13.118%	$146.6914	$146.69	$146.70	$146.70
Purchase #6	$38.97	4.633%	$40.7755	$40.78	$40.80	$40.80
Purchase #7	$170.80	4.478%	$178.4484	$178.45	$178.45	$178.40
7 purchase totals =	$954.78		$1,033.0159	$1,033.02	$1,033.00	$1,033.10