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	$93.98	3.388%	$97.164	$97.16	$97.15	$97.20
Purchase #2	$69.43	4.358%	$72.4558	$72.46	$72.45	$72.50
Purchase #3	$95.41	9.462%	$104.4377	$104.44	$104.45	$104.40
Purchase #4	$36.78	6.473%	$39.1608	$39.16	$39.15	$39.20
Purchase #5	$64.94	6.340%	$69.0572	$69.06	$69.05	$69.10
Purchase #6	$33.40	11.847%	$37.3569	$37.36	$37.35	$37.40
Purchase #7	$150.87	5.139%	$158.6232	$158.62	$158.60	$158.60
7 purchase totals =	$544.81		$578.2556	$578.26	$578.20	$578.40