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	$201.44	13.477%	$228.5881	$228.59	$228.60	$228.60
Purchase #2	$229.41	11.315%	$255.3677	$255.37	$255.35	$255.40
Purchase #3	$42.51	5.110%	$44.6823	$44.68	$44.70	$44.70
Purchase #4	$38.34	5.369%	$40.3985	$40.40	$40.40	$40.40
Purchase #5	$231.62	5.531%	$244.4309	$244.43	$244.45	$244.40
Purchase #6	$82.65	4.699%	$86.5337	$86.53	$86.55	$86.50
Purchase #7	$108.42	13.559%	$123.1207	$123.12	$123.10	$123.10
7 purchase totals =	$934.39		$1,023.1219	$1,023.12	$1,023.15	$1,023.10