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	$161.93	8.611%	$175.8738	$175.87	$175.85	$175.90
Purchase #2	$12.43	3.708%	$12.8909	$12.89	$12.90	$12.90
Purchase #3	$53.92	13.599%	$61.2526	$61.25	$61.25	$61.30
Purchase #4	$218.51	8.817%	$237.776	$237.78	$237.80	$237.80
Purchase #5	$71.80	9.593%	$78.6878	$78.69	$78.70	$78.70
Purchase #6	$58.98	3.702%	$61.1634	$61.16	$61.15	$61.20
Purchase #7	$158.62	9.627%	$173.8903	$173.89	$173.90	$173.90
7 purchase totals =	$736.19		$801.5348	$801.53	$801.55	$801.70