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	$85.54	11.328%	$95.23	$95.23	$95.25	$95.20
Purchase #2	$107.86	12.417%	$121.253	$121.25	$121.25	$121.30
Purchase #3	$10.59	8.513%	$11.4915	$11.49	$11.50	$11.50
Purchase #4	$204.75	11.121%	$227.5202	$227.52	$227.50	$227.50
Purchase #5	$34.89	8.533%	$37.8672	$37.87	$37.85	$37.90
Purchase #6	$95.51	10.799%	$105.8241	$105.82	$105.80	$105.80
Purchase #7	$144.41	8.805%	$157.1253	$157.13	$157.15	$157.10
7 purchase totals =	$683.55		$756.3113	$756.31	$756.30	$756.30