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	$216.65	11.402%	$241.3524	$241.35	$241.35	$241.40
Purchase #2	$32.43	11.659%	$36.211	$36.21	$36.20	$36.20
Purchase #3	$144.60	5.470%	$152.5096	$152.51	$152.50	$152.50
Purchase #4	$236.72	12.466%	$266.2295	$266.23	$266.25	$266.20
Purchase #5	$149.80	12.545%	$168.5924	$168.59	$168.60	$168.60
Purchase #6	$198.51	12.680%	$223.6811	$223.68	$223.70	$223.70
Purchase #7	$52.75	9.286%	$57.6484	$57.65	$57.65	$57.60
7 purchase totals =	$1,031.46		$1,146.2244	$1,146.22	$1,146.25	$1,146.20