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	$85.34	11.489%	$95.1447	$95.14	$95.15	$95.10
Purchase #2	$32.80	13.832%	$37.3369	$37.34	$37.35	$37.30
Purchase #3	$237.84	3.670%	$246.5687	$246.57	$246.55	$246.60
Purchase #4	$146.55	6.196%	$155.6302	$155.63	$155.65	$155.60
Purchase #5	$143.47	6.799%	$153.2245	$153.22	$153.20	$153.20
Purchase #6	$175.67	7.303%	$188.4992	$188.50	$188.50	$188.50
Purchase #7	$158.44	4.231%	$165.1436	$165.14	$165.15	$165.10
7 purchase totals =	$980.11		$1,041.5478	$1,041.54	$1,041.55	$1,041.40