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	$41.37	4.385%	$43.1841	$43.18	$43.20	$43.20
Purchase #2	$18.31	6.772%	$19.55	$19.55	$19.55	$19.60
Purchase #3	$137.76	5.179%	$144.8946	$144.89	$144.90	$144.90
Purchase #4	$6.59	13.691%	$7.4922	$7.49	$7.50	$7.50
Purchase #5	$107.75	12.628%	$121.3567	$121.36	$121.35	$121.40
Purchase #6	$153.64	13.161%	$173.8606	$173.86	$173.85	$173.90
Purchase #7	$179.25	6.259%	$190.4693	$190.47	$190.45	$190.50
7 purchase totals =	$644.67		$700.8075	$700.80	$700.80	$701.00