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	$230.38	3.288%	$237.9549	$237.95	$237.95	$238.00
Purchase #2	$172.78	10.841%	$191.5111	$191.51	$191.50	$191.50
Purchase #3	$64.95	10.679%	$71.886	$71.89	$71.90	$71.90
Purchase #4	$143.53	6.379%	$152.6858	$152.69	$152.70	$152.70
Purchase #5	$129.90	13.312%	$147.1923	$147.19	$147.20	$147.20
Purchase #6	$60.83	4.841%	$63.7748	$63.77	$63.75	$63.80
Purchase #7	$237.72	8.777%	$258.5847	$258.58	$258.60	$258.60
7 purchase totals =	$1,040.09		$1,123.5896	$1,123.58	$1,123.60	$1,123.70