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	$190.60	9.186%	$208.1085	$208.11	$208.10	$208.10
Purchase #2	$45.41	6.698%	$48.4516	$48.45	$48.45	$48.50
Purchase #3	$22.49	13.816%	$25.5972	$25.60	$25.60	$25.60
Purchase #4	$100.61	5.640%	$106.2844	$106.28	$106.30	$106.30
Purchase #5	$30.29	6.676%	$32.3122	$32.31	$32.30	$32.30
Purchase #6	$40.47	5.175%	$42.5643	$42.56	$42.55	$42.60
Purchase #7	$221.50	5.567%	$233.8309	$233.83	$233.85	$233.80
7 purchase totals =	$651.37		$697.1491	$697.14	$697.15	$697.20