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	$47.90	10.647%	$52.9999	$53.00	$53.00	$53.00
Purchase #2	$97.92	13.674%	$111.3096	$111.31	$111.30	$111.30
Purchase #3	$99.78	7.697%	$107.4601	$107.46	$107.45	$107.50
Purchase #4	$132.89	11.390%	$148.0262	$148.03	$148.05	$148.00
Purchase #5	$205.57	9.594%	$225.2924	$225.29	$225.30	$225.30
Purchase #6	$74.66	5.417%	$78.7043	$78.70	$78.70	$78.70
Purchase #7	$212.90	11.674%	$237.7539	$237.75	$237.75	$237.80
7 purchase totals =	$871.62		$961.5464	$961.54	$961.55	$961.60