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	$118.96	3.302%	$122.8881	$122.89	$122.90	$122.90
Purchase #2	$94.69	9.397%	$103.588	$103.59	$103.60	$103.60
Purchase #3	$48.92	13.584%	$55.5653	$55.57	$55.55	$55.60
Purchase #4	$80.50	3.750%	$83.5188	$83.52	$83.50	$83.50
Purchase #5	$23.34	8.193%	$25.2522	$25.25	$25.25	$25.30
Purchase #6	$138.32	4.751%	$144.8916	$144.89	$144.90	$144.90
Purchase #7	$141.81	12.331%	$159.2966	$159.30	$159.30	$159.30
7 purchase totals =	$646.54		$695.0006	$695.01	$695.00	$695.10