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	$245.63	7.130%	$263.1434	$263.14	$263.15	$263.10
Purchase #2	$76.61	7.269%	$82.1788	$82.18	$82.20	$82.20
Purchase #3	$20.81	12.762%	$23.4658	$23.47	$23.45	$23.50
Purchase #4	$246.26	3.562%	$255.0318	$255.03	$255.05	$255.00
Purchase #5	$215.38	12.128%	$241.5013	$241.50	$241.50	$241.50
Purchase #6	$45.83	12.575%	$51.5931	$51.59	$51.60	$51.60
Purchase #7	$146.94	3.743%	$152.44	$152.44	$152.45	$152.40
7 purchase totals =	$997.46		$1,069.3542	$1,069.35	$1,069.40	$1,069.30