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	$107.49	5.384%	$113.2773	$113.28	$113.30	$113.30
Purchase #2	$68.73	4.439%	$71.7809	$71.78	$71.80	$71.80
Purchase #3	$50.70	5.447%	$53.4616	$53.46	$53.45	$53.50
Purchase #4	$199.61	4.314%	$208.2212	$208.22	$208.20	$208.20
Purchase #5	$138.60	5.377%	$146.0525	$146.05	$146.05	$146.10
Purchase #6	$248.90	5.368%	$262.261	$262.26	$262.25	$262.30
Purchase #7	$50.47	9.724%	$55.3777	$55.38	$55.40	$55.40
7 purchase totals =	$864.50		$910.4322	$910.43	$910.45	$910.60