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	$87.55	7.567%	$94.1749	$94.17	$94.15	$94.20
Purchase #2	$216.72	13.738%	$246.493	$246.49	$246.50	$246.50
Purchase #3	$65.53	7.111%	$70.1898	$70.19	$70.20	$70.20
Purchase #4	$144.68	6.637%	$154.2824	$154.28	$154.30	$154.30
Purchase #5	$122.47	4.188%	$127.599	$127.60	$127.60	$127.60
Purchase #6	$22.50	9.267%	$24.5851	$24.59	$24.60	$24.60
Purchase #7	$213.89	4.698%	$223.9386	$223.94	$223.95	$223.90
7 purchase totals =	$873.34		$941.2628	$941.26	$941.30	$941.30