Option for reduced tax Rate via Button


i’m looking to setup an option where by pressing a button I can change the amount of tax to be charged for an order. For example, currently let’s say we have a tax at 17%. Hence, an item of 80 will cost us (80 + 13.60 = 93.60) Image 1

Now let’s say we want to have the option of bringing down the total tax rate, when needed, by pressing a particular button (or payment method). When that is done the rate is reduced to lets say 5% to give us the information in Image 2.

I would be grateful if someone can share on how that can be programmed in Samba.

Image 1:

Image 2:

Discont Name TAX %5 …

Was going to say, could try making a ticket calculation and having it move tax back between accounts to the difference.
Either than ir you need to change tax setup to use calculations rather than built in tax.
Although taxes can be mapped to additional factors but cant remember them from top of my head as not had to do much work with them as nothing like that in uk.