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	$81.36	5.532%	$85.8608	$85.86	$85.85	$85.90
Purchase #2	$168.42	11.855%	$188.3862	$188.39	$188.40	$188.40
Purchase #3	$172.87	13.548%	$196.2904	$196.29	$196.30	$196.30
Purchase #4	$49.40	11.371%	$55.0173	$55.02	$55.00	$55.00
Purchase #5	$177.74	7.160%	$190.4662	$190.47	$190.45	$190.50
Purchase #6	$242.44	8.814%	$263.8087	$263.81	$263.80	$263.80
Purchase #7	$59.38	3.459%	$61.434	$61.43	$61.45	$61.40
7 purchase totals =	$951.61		$1,041.2636	$1,041.27	$1,041.25	$1,041.30