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	$213.83	6.362%	$227.4339	$227.43	$227.45	$227.40
Purchase #2	$99.42	5.680%	$105.0671	$105.07	$105.05	$105.10
Purchase #3	$67.55	9.105%	$73.7004	$73.70	$73.70	$73.70
Purchase #4	$70.84	10.557%	$78.3186	$78.32	$78.30	$78.30
Purchase #5	$198.48	3.314%	$205.0576	$205.06	$205.05	$205.10
Purchase #6	$201.74	7.487%	$216.8443	$216.84	$216.85	$216.80
Purchase #7	$172.39	13.733%	$196.0643	$196.06	$196.05	$196.10
7 purchase totals =	$1,024.25		$1,102.4862	$1,102.48	$1,102.45	$1,102.50