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	$146.57	3.864%	$152.2335	$152.23	$152.25	$152.20
Purchase #2	$93.42	7.624%	$100.5423	$100.54	$100.55	$100.50
Purchase #3	$56.57	10.684%	$62.6139	$62.61	$62.60	$62.60
Purchase #4	$171.36	7.496%	$184.2051	$184.21	$184.20	$184.20
Purchase #5	$216.58	11.508%	$241.504	$241.50	$241.50	$241.50
Purchase #6	$137.53	6.157%	$145.9977	$146.00	$146.00	$146.00
Purchase #7	$209.49	7.272%	$224.7241	$224.72	$224.70	$224.70
7 purchase totals =	$1,031.52		$1,111.8206	$1,111.81	$1,111.80	$1,111.70