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	$218.72	3.141%	$225.59	$225.59	$225.60	$225.60
Purchase #2	$37.46	5.630%	$39.569	$39.57	$39.55	$39.60
Purchase #3	$13.73	3.767%	$14.2472	$14.25	$14.25	$14.20
Purchase #4	$126.75	3.538%	$131.2344	$131.23	$131.25	$131.20
Purchase #5	$241.90	10.594%	$267.5269	$267.53	$267.55	$267.50
Purchase #6	$52.42	8.498%	$56.8747	$56.87	$56.85	$56.90
Purchase #7	$243.75	5.244%	$256.5323	$256.53	$256.55	$256.50
7 purchase totals =	$934.73		$991.5745	$991.57	$991.60	$991.50