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	$144.72	5.683%	$152.9444	$152.94	$152.95	$152.90
Purchase #2	$16.59	6.103%	$17.6025	$17.60	$17.60	$17.60
Purchase #3	$111.61	13.685%	$126.8838	$126.88	$126.90	$126.90
Purchase #4	$95.38	6.808%	$101.8735	$101.87	$101.85	$101.90
Purchase #5	$138.52	5.431%	$146.043	$146.04	$146.05	$146.00
Purchase #6	$7.60	13.384%	$8.6172	$8.62	$8.60	$8.60
Purchase #7	$66.92	11.300%	$74.482	$74.48	$74.50	$74.50
7 purchase totals =	$581.34		$628.4464	$628.43	$628.45	$628.40