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	$195.28	10.733%	$216.2394	$216.24	$216.25	$216.20
Purchase #2	$157.72	8.850%	$171.6782	$171.68	$171.70	$171.70
Purchase #3	$48.40	4.128%	$50.398	$50.40	$50.40	$50.40
Purchase #4	$59.62	7.165%	$63.8918	$63.89	$63.90	$63.90
Purchase #5	$174.54	12.643%	$196.6071	$196.61	$196.60	$196.60
Purchase #6	$132.84	11.704%	$148.3876	$148.39	$148.40	$148.40
Purchase #7	$131.53	12.719%	$148.2593	$148.26	$148.25	$148.30
7 purchase totals =	$899.93		$995.4614	$995.47	$995.50	$995.50