In odoo pos i set 'Allow Global Discount'. I defined a product as `Discount` set both customer tax and vendor tax as Null.  In pos order, selected multiple products, odoo automatically calculated `Total Amount & Tax`. 

But when i apply `Discount` the tax remain same.I think the tax amount should be calculate only for remaining amount.

Example: 

  Subtotal(Untaxed Amount) = 1500

  Tax Amount                           =      25

  Total                                        =  1525

If i apply 100 % Discount, the total amount will be 0.00 and tax remain same as 25.

Is it bug?

How can i calculate tax for remaining amount?

Any solution?