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	$219.55	8.298%	$237.7683	$237.77	$237.75	$237.80
Purchase #2	$221.75	10.422%	$244.8608	$244.86	$244.85	$244.90
Purchase #3	$172.32	11.669%	$192.428	$192.43	$192.45	$192.40
Purchase #4	$14.60	8.590%	$15.8541	$15.85	$15.85	$15.90
Purchase #5	$122.42	11.127%	$136.0417	$136.04	$136.05	$136.00
Purchase #6	$154.89	4.278%	$161.5162	$161.52	$161.50	$161.50
Purchase #7	$167.72	10.553%	$185.4195	$185.42	$185.40	$185.40
7 purchase totals =	$1,073.25		$1,173.8886	$1,173.89	$1,173.85	$1,173.90