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	$168.85	9.771%	$185.3483	$185.35	$185.35	$185.30
Purchase #2	$190.83	13.429%	$216.4566	$216.46	$216.45	$216.50
Purchase #3	$20.79	8.813%	$22.6222	$22.62	$22.60	$22.60
Purchase #4	$93.33	11.588%	$104.1451	$104.15	$104.15	$104.10
Purchase #5	$102.40	3.494%	$105.9779	$105.98	$106.00	$106.00
Purchase #6	$114.25	9.638%	$125.2614	$125.26	$125.25	$125.30
Purchase #7	$178.43	5.403%	$188.0706	$188.07	$188.05	$188.10
7 purchase totals =	$868.88		$947.8821	$947.89	$947.85	$947.90