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	$50.84	9.444%	$55.6413	$55.64	$55.65	$55.60
Purchase #2	$146.66	4.196%	$152.8139	$152.81	$152.80	$152.80
Purchase #3	$53.35	4.299%	$55.6435	$55.64	$55.65	$55.60
Purchase #4	$238.73	13.353%	$270.6076	$270.61	$270.60	$270.60
Purchase #5	$89.45	6.729%	$95.4691	$95.47	$95.45	$95.50
Purchase #6	$158.61	10.488%	$175.245	$175.25	$175.25	$175.20
Purchase #7	$223.99	13.372%	$253.9419	$253.94	$253.95	$253.90
7 purchase totals =	$961.63		$1,059.3623	$1,059.36	$1,059.35	$1,059.20