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	$9.88	10.864%	$10.9534	$10.95	$10.95	$11.00
Purchase #2	$76.79	13.118%	$86.8633	$86.86	$86.85	$86.90
Purchase #3	$78.63	5.675%	$83.0923	$83.09	$83.10	$83.10
Purchase #4	$86.62	9.727%	$95.0455	$95.05	$95.05	$95.00
Purchase #5	$95.58	4.780%	$100.1487	$100.15	$100.15	$100.10
Purchase #6	$224.34	11.657%	$250.4913	$250.49	$250.50	$250.50
Purchase #7	$150.61	5.596%	$159.0381	$159.04	$159.05	$159.00
7 purchase totals =	$722.45		$785.6326	$785.63	$785.65	$785.60