I can answer this

Had to do this for our pole display.
Two Actions
Action Name - Update Tendered Amount
Action Type - Update Program Setting
Setting Name - TENDERED
Setting Value - [Setting Value]
Update Type - Update
Action Name - Update Change Due
Action Type - Update Program Setting
Setting Name - CHANGEDUE
Setting Value - [Setting Value]
Update Type - Update
One Rule
Rule Name - Change Updated
Event Name - Change Amount Updated
Actions - Update Tendered Amount
Setting Value - [TenderedAmount]
Actions - Update Change Due
Settings Value - [ChangeAmount]
Printer Template
Add the following to the Footer
<J00>Tendered|${SETTING:TENDERED}
<J00>Change Due|${SETTING:CHANGEDUE}
This is a quick run down, you can use this link as a reference for more detailed step by step -
http://forum2.sambapos.org/index.php/topic,80.msg379.html#msg379Have Fun.