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	$130.26	10.572%	$144.0311	$144.03	$144.05	$144.00
Purchase #2	$100.38	6.634%	$107.0392	$107.04	$107.05	$107.00
Purchase #3	$154.34	11.503%	$172.0937	$172.09	$172.10	$172.10
Purchase #4	$234.33	8.869%	$255.1127	$255.11	$255.10	$255.10
Purchase #5	$9.90	12.787%	$11.1659	$11.17	$11.15	$11.20
Purchase #6	$231.80	11.359%	$258.1302	$258.13	$258.15	$258.10
Purchase #7	$111.55	4.510%	$116.5809	$116.58	$116.60	$116.60
7 purchase totals =	$972.56		$1,064.1537	$1,064.15	$1,064.20	$1,064.10