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	$217.60	4.753%	$227.9425	$227.94	$227.95	$227.90
Purchase #2	$197.47	7.578%	$212.4343	$212.43	$212.45	$212.40
Purchase #3	$157.73	7.493%	$169.5487	$169.55	$169.55	$169.50
Purchase #4	$155.96	11.615%	$174.0748	$174.07	$174.05	$174.10
Purchase #5	$235.95	11.243%	$262.4779	$262.48	$262.50	$262.50
Purchase #6	$161.82	6.708%	$172.6749	$172.67	$172.65	$172.70
Purchase #7	$78.84	4.698%	$82.5439	$82.54	$82.55	$82.50
7 purchase totals =	$1,205.37		$1,301.6970	$1,301.68	$1,301.70	$1,301.60