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	$65.38	10.735%	$72.3985	$72.40	$72.40	$72.40
Purchase #2	$136.58	8.426%	$148.0882	$148.09	$148.10	$148.10
Purchase #3	$159.86	10.264%	$176.268	$176.27	$176.25	$176.30
Purchase #4	$130.44	13.271%	$147.7507	$147.75	$147.75	$147.80
Purchase #5	$70.74	11.392%	$78.7987	$78.80	$78.80	$78.80
Purchase #6	$196.34	10.778%	$217.5015	$217.50	$217.50	$217.50
Purchase #7	$172.88	11.149%	$192.1544	$192.15	$192.15	$192.20
7 purchase totals =	$932.22		$1,032.9600	$1,032.96	$1,032.95	$1,033.10