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	$182.48	8.476%	$197.947	$197.95	$197.95	$197.90
Purchase #2	$38.64	3.379%	$39.9456	$39.95	$39.95	$39.90
Purchase #3	$87.58	5.648%	$92.5265	$92.53	$92.55	$92.50
Purchase #4	$40.80	4.436%	$42.6099	$42.61	$42.60	$42.60
Purchase #5	$52.49	13.663%	$59.6617	$59.66	$59.65	$59.70
Purchase #6	$15.67	13.586%	$17.7989	$17.80	$17.80	$17.80
Purchase #7	$47.86	6.385%	$50.9159	$50.92	$50.90	$50.90
7 purchase totals =	$465.52		$501.4055	$501.42	$501.40	$501.30