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	$86.48	10.141%	$95.2499	$95.25	$95.25	$95.20
Purchase #2	$20.81	5.108%	$21.873	$21.87	$21.85	$21.90
Purchase #3	$241.39	12.524%	$271.6217	$271.62	$271.60	$271.60
Purchase #4	$195.70	9.823%	$214.9236	$214.92	$214.90	$214.90
Purchase #5	$50.59	10.333%	$55.8175	$55.82	$55.80	$55.80
Purchase #6	$125.88	12.634%	$141.7837	$141.78	$141.80	$141.80
Purchase #7	$86.65	10.468%	$95.7205	$95.72	$95.70	$95.70
7 purchase totals =	$807.50		$896.9899	$896.98	$896.90	$896.90