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	$184.47	11.379%	$205.4608	$205.46	$205.45	$205.50
Purchase #2	$242.95	8.871%	$264.5021	$264.50	$264.50	$264.50
Purchase #3	$215.32	12.184%	$241.5546	$241.55	$241.55	$241.60
Purchase #4	$13.35	10.521%	$14.7546	$14.75	$14.75	$14.80
Purchase #5	$209.54	13.860%	$238.5822	$238.58	$238.60	$238.60
Purchase #6	$196.71	13.233%	$222.7406	$222.74	$222.75	$222.70
Purchase #7	$233.63	10.709%	$258.6494	$258.65	$258.65	$258.60
7 purchase totals =	$1,295.97		$1,446.2443	$1,446.23	$1,446.25	$1,446.30