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	$151.77	11.717%	$169.5529	$169.55	$169.55	$169.60
Purchase #2	$56.70	4.144%	$59.0496	$59.05	$59.05	$59.00
Purchase #3	$213.45	9.487%	$233.7	$233.70	$233.70	$233.70
Purchase #4	$139.89	8.108%	$151.2323	$151.23	$151.25	$151.20
Purchase #5	$248.78	9.479%	$272.3619	$272.36	$272.35	$272.40
Purchase #6	$243.55	4.610%	$254.7777	$254.78	$254.80	$254.80
Purchase #7	$62.39	3.261%	$64.4245	$64.42	$64.40	$64.40
7 purchase totals =	$1,116.53		$1,205.0989	$1,205.09	$1,205.10	$1,205.10