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	$97.58	11.643%	$108.9412	$108.94	$108.95	$108.90
Purchase #2	$41.54	9.528%	$45.4979	$45.50	$45.50	$45.50
Purchase #3	$149.52	9.242%	$163.3386	$163.34	$163.35	$163.30
Purchase #4	$125.75	5.767%	$133.002	$133.00	$133.00	$133.00
Purchase #5	$54.86	8.227%	$59.3733	$59.37	$59.35	$59.40
Purchase #6	$66.70	8.617%	$72.4475	$72.45	$72.45	$72.40
Purchase #7	$166.44	10.843%	$184.4871	$184.49	$184.50	$184.50
7 purchase totals =	$702.39		$767.0876	$767.09	$767.10	$767.00