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	$124.68	13.549%	$141.5729	$141.57	$141.55	$141.60
Purchase #2	$123.65	11.449%	$137.8067	$137.81	$137.80	$137.80
Purchase #3	$147.89	13.211%	$167.4277	$167.43	$167.45	$167.40
Purchase #4	$208.44	7.388%	$223.8395	$223.84	$223.85	$223.80
Purchase #5	$231.46	11.222%	$257.4344	$257.43	$257.45	$257.40
Purchase #6	$241.90	8.406%	$262.2341	$262.23	$262.25	$262.20
Purchase #7	$247.94	9.367%	$271.1645	$271.16	$271.15	$271.20
7 purchase totals =	$1,325.96		$1,461.4798	$1,461.47	$1,461.50	$1,461.40