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	$208.37	3.571%	$215.8109	$215.81	$215.80	$215.80
Purchase #2	$76.91	5.839%	$81.4008	$81.40	$81.40	$81.40
Purchase #3	$64.78	12.601%	$72.9429	$72.94	$72.95	$72.90
Purchase #4	$31.55	3.128%	$32.5369	$32.54	$32.55	$32.50
Purchase #5	$106.45	10.758%	$117.9019	$117.90	$117.90	$117.90
Purchase #6	$247.27	6.391%	$263.073	$263.07	$263.05	$263.10
Purchase #7	$76.69	8.688%	$83.3528	$83.35	$83.35	$83.40
7 purchase totals =	$812.02		$867.0192	$867.01	$867.00	$867.00