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	$214.81	7.763%	$231.4857	$231.49	$231.50	$231.50
Purchase #2	$219.51	10.123%	$241.731	$241.73	$241.75	$241.70
Purchase #3	$83.61	4.472%	$87.349	$87.35	$87.35	$87.30
Purchase #4	$83.50	7.150%	$89.4703	$89.47	$89.45	$89.50
Purchase #5	$182.50	10.331%	$201.3541	$201.35	$201.35	$201.40
Purchase #6	$45.85	12.237%	$51.4607	$51.46	$51.45	$51.50
Purchase #7	$119.67	10.590%	$132.3431	$132.34	$132.35	$132.30
7 purchase totals =	$949.45		$1,035.1939	$1,035.19	$1,035.20	$1,035.20