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	$233.55	12.176%	$261.987	$261.99	$262.00	$262.00
Purchase #2	$167.46	3.104%	$172.658	$172.66	$172.65	$172.70
Purchase #3	$182.46	13.661%	$207.3859	$207.39	$207.40	$207.40
Purchase #4	$216.35	6.647%	$230.7308	$230.73	$230.75	$230.70
Purchase #5	$65.60	10.667%	$72.5976	$72.60	$72.60	$72.60
Purchase #6	$55.42	5.454%	$58.4426	$58.44	$58.45	$58.40
Purchase #7	$11.57	13.496%	$13.1315	$13.13	$13.15	$13.10
7 purchase totals =	$932.41		$1,016.9334	$1,016.94	$1,017.00	$1,016.90