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	$233.25	13.561%	$264.881	$264.88	$264.90	$264.90
Purchase #2	$22.71	12.737%	$25.6026	$25.60	$25.60	$25.60
Purchase #3	$200.72	4.211%	$209.1723	$209.17	$209.15	$209.20
Purchase #4	$208.76	12.406%	$234.6588	$234.66	$234.65	$234.70
Purchase #5	$133.87	13.743%	$152.2678	$152.27	$152.25	$152.30
Purchase #6	$45.81	10.441%	$50.593	$50.59	$50.60	$50.60
Purchase #7	$107.70	9.358%	$117.7786	$117.78	$117.80	$117.80
7 purchase totals =	$952.82		$1,054.9541	$1,054.95	$1,054.95	$1,055.10