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	$43.58	9.570%	$47.7506	$47.75	$47.75	$47.80
Purchase #2	$27.72	13.166%	$31.3696	$31.37	$31.35	$31.40
Purchase #3	$37.65	10.523%	$41.6119	$41.61	$41.60	$41.60
Purchase #4	$80.72	5.169%	$84.8924	$84.89	$84.90	$84.90
Purchase #5	$27.46	12.384%	$30.8606	$30.86	$30.85	$30.90
Purchase #6	$119.85	10.532%	$132.4726	$132.47	$132.45	$132.50
Purchase #7	$93.78	4.368%	$97.8763	$97.88	$97.90	$97.90
7 purchase totals =	$430.76		$466.8340	$466.83	$466.80	$467.00