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	$60.51	13.451%	$68.6492	$68.65	$68.65	$68.60
Purchase #2	$29.92	10.510%	$33.0646	$33.06	$33.05	$33.10
Purchase #3	$82.81	5.133%	$87.0606	$87.06	$87.05	$87.10
Purchase #4	$69.39	11.590%	$77.4323	$77.43	$77.45	$77.40
Purchase #5	$150.35	9.707%	$164.9445	$164.94	$164.95	$164.90
Purchase #6	$98.38	13.214%	$111.3799	$111.38	$111.40	$111.40
Purchase #7	$10.61	3.178%	$10.9472	$10.95	$10.95	$10.90
7 purchase totals =	$501.97		$553.4783	$553.47	$553.50	$553.40