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	$214.49	3.753%	$222.5398	$222.54	$222.55	$222.50
Purchase #2	$220.39	11.334%	$245.369	$245.37	$245.35	$245.40
Purchase #3	$138.94	9.346%	$151.9253	$151.93	$151.95	$151.90
Purchase #4	$197.37	12.846%	$222.7242	$222.72	$222.70	$222.70
Purchase #5	$78.84	10.336%	$86.9889	$86.99	$87.00	$87.00
Purchase #6	$37.44	12.364%	$42.0691	$42.07	$42.05	$42.10
Purchase #7	$180.41	8.552%	$195.8387	$195.84	$195.85	$195.80
7 purchase totals =	$1,067.88		$1,167.4550	$1,167.46	$1,167.45	$1,167.40