Add new fields in partial refund - Prestashop 1.7.7.2

[WidadShaimy]

Hello,

I would like to add a new field called Shipping Tax. And I would like to know how to add it and also use it. In fact the taxes I pay are never the same, it depends on the state (US). So I would like to know if you have any idea how to add, then recuperate and add it to the Shipping that has been put in the Shipping field.

And so also in the database, on the ps_order_slip table, we will have this example:

total_shipping_tax_excl : 9.99
total_shipping_tax_incl : 10.79 (9.99 + 0.80)

Can anyone help me please?