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	$190.38	8.603%	$206.7584	$206.76	$206.75	$206.80
Purchase #2	$173.83	10.515%	$192.1082	$192.11	$192.10	$192.10
Purchase #3	$33.52	11.570%	$37.3983	$37.40	$37.40	$37.40
Purchase #4	$109.69	13.162%	$124.1274	$124.13	$124.15	$124.10
Purchase #5	$51.46	3.397%	$53.2081	$53.21	$53.20	$53.20
Purchase #6	$155.60	10.828%	$172.4484	$172.45	$172.45	$172.40
Purchase #7	$138.31	5.763%	$146.2808	$146.28	$146.30	$146.30
7 purchase totals =	$852.79		$932.3296	$932.34	$932.35	$932.30