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	$153.31	13.462%	$173.9486	$173.95	$173.95	$173.90
Purchase #2	$145.51	7.527%	$156.4625	$156.46	$156.45	$156.50
Purchase #3	$15.47	11.236%	$17.2082	$17.21	$17.20	$17.20
Purchase #4	$12.86	7.247%	$13.792	$13.79	$13.80	$13.80
Purchase #5	$59.40	12.620%	$66.8963	$66.90	$66.90	$66.90
Purchase #6	$44.63	8.713%	$48.5186	$48.52	$48.50	$48.50
Purchase #7	$207.46	7.311%	$222.6274	$222.63	$222.65	$222.60
7 purchase totals =	$638.64		$699.4536	$699.46	$699.45	$699.40