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	$83.91	12.672%	$94.5431	$94.54	$94.55	$94.50
Purchase #2	$224.28	13.776%	$255.1768	$255.18	$255.20	$255.20
Purchase #3	$35.67	8.561%	$38.7237	$38.72	$38.70	$38.70
Purchase #4	$51.38	6.643%	$54.7932	$54.79	$54.80	$54.80
Purchase #5	$231.61	8.481%	$251.2528	$251.25	$251.25	$251.30
Purchase #6	$68.90	3.715%	$71.4596	$71.46	$71.45	$71.50
Purchase #7	$164.58	12.860%	$185.745	$185.75	$185.75	$185.70
7 purchase totals =	$860.33		$951.6942	$951.69	$951.70	$951.70