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	$175.89	10.809%	$194.902	$194.90	$194.90	$194.90
Purchase #2	$9.50	8.671%	$10.3237	$10.32	$10.30	$10.30
Purchase #3	$196.82	11.105%	$218.6769	$218.68	$218.70	$218.70
Purchase #4	$36.69	10.202%	$40.4331	$40.43	$40.45	$40.40
Purchase #5	$109.27	9.717%	$119.8878	$119.89	$119.90	$119.90
Purchase #6	$107.72	3.388%	$111.3696	$111.37	$111.35	$111.40
Purchase #7	$13.63	5.841%	$14.4261	$14.43	$14.45	$14.40
7 purchase totals =	$649.52		$710.0192	$710.02	$710.05	$710.00