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	$140.44	8.230%	$151.9982	$152.00	$152.00	$152.00
Purchase #2	$17.93	8.536%	$19.4605	$19.46	$19.45	$19.50
Purchase #3	$125.25	9.521%	$137.1751	$137.18	$137.20	$137.20
Purchase #4	$240.43	3.168%	$248.0468	$248.05	$248.05	$248.00
Purchase #5	$48.48	4.561%	$50.6912	$50.69	$50.70	$50.70
Purchase #6	$31.94	5.166%	$33.59	$33.59	$33.60	$33.60
Purchase #7	$114.63	7.706%	$123.4634	$123.46	$123.45	$123.50
7 purchase totals =	$719.10		$764.4252	$764.43	$764.45	$764.50