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	$176.72	10.785%	$195.7793	$195.78	$195.80	$195.80
Purchase #2	$140.29	4.375%	$146.4277	$146.43	$146.45	$146.40
Purchase #3	$133.77	5.106%	$140.6003	$140.60	$140.60	$140.60
Purchase #4	$246.74	4.823%	$258.6403	$258.64	$258.65	$258.60
Purchase #5	$142.95	13.248%	$161.888	$161.89	$161.90	$161.90
Purchase #6	$59.93	7.690%	$64.5386	$64.54	$64.55	$64.50
Purchase #7	$140.93	10.407%	$155.5966	$155.60	$155.60	$155.60
7 purchase totals =	$1,041.33		$1,123.4708	$1,123.48	$1,123.55	$1,123.40