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	$85.52	10.698%	$94.6689	$94.67	$94.65	$94.70
Purchase #2	$120.43	5.105%	$126.578	$126.58	$126.60	$126.60
Purchase #3	$172.78	13.576%	$196.2366	$196.24	$196.25	$196.20
Purchase #4	$89.46	6.277%	$95.0754	$95.08	$95.10	$95.10
Purchase #5	$44.76	8.514%	$48.5709	$48.57	$48.55	$48.60
Purchase #6	$156.67	3.168%	$161.6333	$161.63	$161.65	$161.60
Purchase #7	$19.59	5.757%	$20.7178	$20.72	$20.70	$20.70
7 purchase totals =	$689.21		$743.4809	$743.49	$743.50	$743.50