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	$34.68	10.350%	$38.2694	$38.27	$38.25	$38.30
Purchase #2	$82.33	13.698%	$93.6076	$93.61	$93.60	$93.60
Purchase #3	$122.86	3.325%	$126.9451	$126.95	$126.95	$126.90
Purchase #4	$189.90	3.455%	$196.461	$196.46	$196.45	$196.50
Purchase #5	$151.94	6.677%	$162.085	$162.09	$162.10	$162.10
Purchase #6	$77.67	11.389%	$86.5158	$86.52	$86.50	$86.50
Purchase #7	$49.94	11.762%	$55.8139	$55.81	$55.80	$55.80
7 purchase totals =	$709.32		$759.6978	$759.71	$759.65	$759.70