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	$216.45	4.365%	$225.898	$225.90	$225.90	$225.90
Purchase #2	$145.84	9.532%	$159.7415	$159.74	$159.75	$159.70
Purchase #3	$209.84	5.610%	$221.612	$221.61	$221.60	$221.60
Purchase #4	$79.67	3.418%	$82.3931	$82.39	$82.40	$82.40
Purchase #5	$87.73	13.511%	$99.5832	$99.58	$99.60	$99.60
Purchase #6	$134.48	3.733%	$139.5001	$139.50	$139.50	$139.50
Purchase #7	$100.55	8.175%	$108.77	$108.77	$108.75	$108.80
7 purchase totals =	$974.56		$1,037.4979	$1,037.49	$1,037.50	$1,037.50