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	$205.68	6.634%	$219.3248	$219.32	$219.30	$219.30
Purchase #2	$11.61	5.525%	$12.2515	$12.25	$12.25	$12.30
Purchase #3	$134.45	7.341%	$144.32	$144.32	$144.30	$144.30
Purchase #4	$146.31	13.131%	$165.522	$165.52	$165.50	$165.50
Purchase #5	$208.91	5.856%	$221.1438	$221.14	$221.15	$221.10
Purchase #6	$43.65	5.692%	$46.1346	$46.13	$46.15	$46.10
Purchase #7	$75.26	3.698%	$78.0431	$78.04	$78.05	$78.00
7 purchase totals =	$825.87		$886.7398	$886.72	$886.70	$886.60