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	$95.83	8.466%	$103.943	$103.94	$103.95	$103.90
Purchase #2	$183.69	4.212%	$191.427	$191.43	$191.45	$191.40
Purchase #3	$95.95	4.764%	$100.5211	$100.52	$100.50	$100.50
Purchase #4	$20.47	7.669%	$22.0398	$22.04	$22.05	$22.00
Purchase #5	$242.71	13.747%	$276.0753	$276.08	$276.10	$276.10
Purchase #6	$217.82	8.319%	$235.9404	$235.94	$235.95	$235.90
Purchase #7	$169.60	3.248%	$175.1086	$175.11	$175.10	$175.10
7 purchase totals =	$1,026.07		$1,105.0552	$1,105.06	$1,105.10	$1,104.90