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	$229.66	11.667%	$256.4544	$256.45	$256.45	$256.50
Purchase #2	$18.39	6.412%	$19.5692	$19.57	$19.55	$19.60
Purchase #3	$37.51	4.654%	$39.2557	$39.26	$39.25	$39.30
Purchase #4	$56.54	6.660%	$60.3056	$60.31	$60.30	$60.30
Purchase #5	$143.32	7.517%	$154.0934	$154.09	$154.10	$154.10
Purchase #6	$58.80	11.528%	$65.5785	$65.58	$65.60	$65.60
Purchase #7	$169.64	4.281%	$176.9023	$176.90	$176.90	$176.90
7 purchase totals =	$713.86		$772.1591	$772.16	$772.15	$772.30