You can use the following link to set up the change due and amount tendered:
http://forum2.sambapos.org/index.php/topic,218.msg1144.html#msg1144You need to make sure you have the Tax Templates set up for relevant Foods and Drinks
You can also perform calculations in ticket templates so you can therefore print net of tax and gross of tax depending on your requirements, an example below:
[= Format (ToNumber (ToNumber ('{TICKET TOTAL}') - (ToNumber ('{TAX TOTAL}'))))]
This takes the total tax amount away from the ticket total leaving an amount net of tax.
You also need to decide if you are showing the menu items inclusive of tax or net of tax.
Hope this information helps setting up your template