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	$93.52	3.105%	$96.4238	$96.42	$96.40	$96.40
Purchase #2	$188.41	10.806%	$208.7696	$208.77	$208.75	$208.80
Purchase #3	$145.38	4.117%	$151.3653	$151.37	$151.35	$151.40
Purchase #4	$58.81	9.743%	$64.5399	$64.54	$64.55	$64.50
Purchase #5	$37.90	13.122%	$42.8732	$42.87	$42.85	$42.90
Purchase #6	$144.73	9.603%	$158.6284	$158.63	$158.65	$158.60
Purchase #7	$226.55	8.216%	$245.1633	$245.16	$245.15	$245.20
7 purchase totals =	$895.30		$967.7635	$967.76	$967.70	$967.80