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	$86.87	10.109%	$95.6517	$95.65	$95.65	$95.70
Purchase #2	$21.56	11.651%	$24.072	$24.07	$24.05	$24.10
Purchase #3	$159.82	5.800%	$169.0896	$169.09	$169.10	$169.10
Purchase #4	$38.50	11.237%	$42.8262	$42.83	$42.85	$42.80
Purchase #5	$68.60	11.162%	$76.2571	$76.26	$76.25	$76.30
Purchase #6	$40.64	3.672%	$42.1323	$42.13	$42.15	$42.10
Purchase #7	$96.69	12.102%	$108.3914	$108.39	$108.40	$108.40
7 purchase totals =	$512.68		$558.4203	$558.42	$558.45	$558.50