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	$246.61	5.183%	$259.3918	$259.39	$259.40	$259.40
Purchase #2	$238.46	5.859%	$252.4314	$252.43	$252.45	$252.40
Purchase #3	$73.85	6.302%	$78.504	$78.50	$78.50	$78.50
Purchase #4	$225.29	9.370%	$246.3997	$246.40	$246.40	$246.40
Purchase #5	$100.63	13.703%	$114.4193	$114.42	$114.40	$114.40
Purchase #6	$217.42	7.381%	$233.4678	$233.47	$233.45	$233.50
Purchase #7	$205.91	10.307%	$227.1331	$227.13	$227.15	$227.10
7 purchase totals =	$1,308.17		$1,411.7471	$1,411.74	$1,411.75	$1,411.70