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	$196.30	8.152%	$212.3024	$212.30	$212.30	$212.30
Purchase #2	$65.61	5.411%	$69.1602	$69.16	$69.15	$69.20
Purchase #3	$192.85	11.776%	$215.56	$215.56	$215.55	$215.60
Purchase #4	$80.75	3.826%	$83.8395	$83.84	$83.85	$83.80
Purchase #5	$59.35	12.571%	$66.8109	$66.81	$66.80	$66.80
Purchase #6	$55.82	8.584%	$60.6116	$60.61	$60.60	$60.60
Purchase #7	$87.73	12.726%	$98.8945	$98.89	$98.90	$98.90
7 purchase totals =	$738.41		$807.1791	$807.17	$807.15	$807.20