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	$116.57	7.373%	$125.1647	$125.16	$125.15	$125.20
Purchase #2	$242.70	4.106%	$252.6653	$252.67	$252.65	$252.70
Purchase #3	$59.64	9.181%	$65.1155	$65.12	$65.10	$65.10
Purchase #4	$45.86	12.654%	$51.6631	$51.66	$51.65	$51.70
Purchase #5	$84.61	5.749%	$89.4742	$89.47	$89.45	$89.50
Purchase #6	$249.57	13.739%	$283.8584	$283.86	$283.85	$283.90
Purchase #7	$243.61	4.828%	$255.3715	$255.37	$255.35	$255.40
7 purchase totals =	$1,042.56		$1,123.3127	$1,123.31	$1,123.20	$1,123.50