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	$181.57	10.562%	$200.7474	$200.75	$200.75	$200.70
Purchase #2	$95.90	5.520%	$101.1937	$101.19	$101.20	$101.20
Purchase #3	$139.77	13.350%	$158.4293	$158.43	$158.45	$158.40
Purchase #4	$236.25	7.541%	$254.0656	$254.07	$254.05	$254.10
Purchase #5	$51.33	8.761%	$55.827	$55.83	$55.85	$55.80
Purchase #6	$129.79	11.467%	$144.673	$144.67	$144.65	$144.70
Purchase #7	$48.96	10.480%	$54.091	$54.09	$54.10	$54.10
7 purchase totals =	$883.57		$969.0270	$969.03	$969.05	$969.00