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	$205.57	5.534%	$216.9462	$216.95	$216.95	$216.90
Purchase #2	$241.49	13.300%	$273.6082	$273.61	$273.60	$273.60
Purchase #3	$132.52	8.486%	$143.7656	$143.77	$143.75	$143.80
Purchase #4	$66.52	4.770%	$69.693	$69.69	$69.70	$69.70
Purchase #5	$20.89	12.320%	$23.4636	$23.46	$23.45	$23.50
Purchase #6	$56.77	4.154%	$59.1282	$59.13	$59.15	$59.10
Purchase #7	$151.63	5.813%	$160.4443	$160.44	$160.45	$160.40
7 purchase totals =	$875.39		$947.0491	$947.05	$947.05	$947.00