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	$173.94	12.600%	$195.8564	$195.86	$195.85	$195.90
Purchase #2	$50.34	6.700%	$53.7128	$53.71	$53.70	$53.70
Purchase #3	$74.54	5.314%	$78.5011	$78.50	$78.50	$78.50
Purchase #4	$214.88	13.699%	$244.3164	$244.32	$244.30	$244.30
Purchase #5	$241.83	8.311%	$261.9285	$261.93	$261.95	$261.90
Purchase #6	$71.72	3.435%	$74.1836	$74.18	$74.20	$74.20
Purchase #7	$207.52	4.300%	$216.4434	$216.44	$216.45	$216.40
7 purchase totals =	$1,034.77		$1,124.9422	$1,124.94	$1,124.95	$1,124.90