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	$233.51	11.739%	$260.9217	$260.92	$260.90	$260.90
Purchase #2	$23.55	8.240%	$25.4905	$25.49	$25.50	$25.50
Purchase #3	$249.69	9.566%	$273.5753	$273.58	$273.60	$273.60
Purchase #4	$111.34	4.703%	$116.5763	$116.58	$116.60	$116.60
Purchase #5	$47.58	3.182%	$49.094	$49.09	$49.10	$49.10
Purchase #6	$226.35	13.320%	$256.4998	$256.50	$256.50	$256.50
Purchase #7	$172.36	7.428%	$185.1629	$185.16	$185.15	$185.20
7 purchase totals =	$1,064.38		$1,167.3205	$1,167.32	$1,167.35	$1,167.40