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	$113.95	11.222%	$126.7375	$126.74	$126.75	$126.70
Purchase #2	$138.53	9.312%	$151.4299	$151.43	$151.45	$151.40
Purchase #3	$241.90	6.863%	$258.5016	$258.50	$258.50	$258.50
Purchase #4	$231.57	10.386%	$255.6209	$255.62	$255.60	$255.60
Purchase #5	$11.89	13.535%	$13.4993	$13.50	$13.50	$13.50
Purchase #6	$151.53	4.253%	$157.9746	$157.97	$157.95	$158.00
Purchase #7	$41.54	7.858%	$44.8042	$44.80	$44.80	$44.80
7 purchase totals =	$930.91		$1,008.5680	$1,008.56	$1,008.55	$1,008.50