Why is the discount button taking tax off of my total when some of my items are taxed and some not?

[MsJjAw]

What I am talking about is I ring up a taxable item and the a non taxable item and when I hit the discount button it taxes every item.  

Example:

Rv Site (tax of 10%).        $96.00

Tax                                    $   4.80

discount                           $48.00

People (No tax)                $ 2.00

Now my balance is $4.90 for tax when my people time has not tax.  Why is it adding tax to people when I put my discount in?

[VanKalkerFarms]

First thing I saw is 10% tax on $96 is $9.60, not $4.80.  so you're giving 50% off by taking $48 off so now the tax is $4.80.  even if it was taxing the people of $2.00 that's 20¢, not 10¢, so I'm not exactly sure where the $4.90 is coming from without seeing the actual transaction.