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	$94.81	13.874%	$107.9639	$107.96	$107.95	$108.00
Purchase #2	$57.39	8.215%	$62.1046	$62.10	$62.10	$62.10
Purchase #3	$61.72	12.391%	$69.3677	$69.37	$69.35	$69.40
Purchase #4	$100.52	4.351%	$104.8936	$104.89	$104.90	$104.90
Purchase #5	$139.50	9.344%	$152.5349	$152.53	$152.55	$152.50
Purchase #6	$197.97	5.380%	$208.6208	$208.62	$208.60	$208.60
Purchase #7	$171.43	10.854%	$190.037	$190.04	$190.05	$190.00
7 purchase totals =	$823.34		$895.5225	$895.51	$895.50	$895.50