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	$215.77	3.865%	$224.1095	$224.11	$224.10	$224.10
Purchase #2	$12.55	7.238%	$13.4584	$13.46	$13.45	$13.50
Purchase #3	$45.57	13.771%	$51.8454	$51.85	$51.85	$51.80
Purchase #4	$87.69	13.598%	$99.6141	$99.61	$99.60	$99.60
Purchase #5	$127.66	12.662%	$143.8243	$143.82	$143.80	$143.80
Purchase #6	$190.32	5.334%	$200.4717	$200.47	$200.45	$200.50
Purchase #7	$136.58	9.168%	$149.1017	$149.10	$149.10	$149.10
7 purchase totals =	$816.14		$882.4251	$882.42	$882.35	$882.40