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	$143.91	6.246%	$152.8986	$152.90	$152.90	$152.90
Purchase #2	$15.59	13.226%	$17.6519	$17.65	$17.65	$17.70
Purchase #3	$43.25	11.504%	$48.2255	$48.23	$48.25	$48.20
Purchase #4	$172.76	8.269%	$187.0455	$187.05	$187.05	$187.00
Purchase #5	$87.29	9.535%	$95.6131	$95.61	$95.60	$95.60
Purchase #6	$72.91	7.790%	$78.5897	$78.59	$78.60	$78.60
Purchase #7	$132.45	13.762%	$150.6778	$150.68	$150.70	$150.70
7 purchase totals =	$668.16		$730.7021	$730.71	$730.75	$730.70