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	$176.78	11.248%	$196.6642	$196.66	$196.65	$196.70
Purchase #2	$220.67	11.676%	$246.4354	$246.44	$246.45	$246.40
Purchase #3	$41.38	9.681%	$45.386	$45.39	$45.40	$45.40
Purchase #4	$228.81	8.563%	$248.403	$248.40	$248.40	$248.40
Purchase #5	$177.60	10.604%	$196.4327	$196.43	$196.45	$196.40
Purchase #6	$10.46	12.871%	$11.8063	$11.81	$11.80	$11.80
Purchase #7	$152.37	13.733%	$173.295	$173.30	$173.30	$173.30
7 purchase totals =	$1,008.07		$1,118.4226	$1,118.43	$1,118.45	$1,118.40