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	$94.60	7.428%	$101.6269	$101.63	$101.65	$101.60
Purchase #2	$156.94	5.516%	$165.5968	$165.60	$165.60	$165.60
Purchase #3	$214.29	3.676%	$222.1673	$222.17	$222.15	$222.20
Purchase #4	$59.47	11.177%	$66.117	$66.12	$66.10	$66.10
Purchase #5	$166.42	4.130%	$173.2931	$173.29	$173.30	$173.30
Purchase #6	$167.58	4.729%	$175.5049	$175.50	$175.50	$175.50
Purchase #7	$129.80	8.727%	$141.1276	$141.13	$141.15	$141.10
7 purchase totals =	$989.10		$1,045.4336	$1,045.44	$1,045.45	$1,045.40