How can I setup a 3% blanket discount for cash?

[MrJeezy]

I'd like to offer a blanket 3% discount when customers pay cash after basically raising the price 3% across the board. Right now, for example, a large coffee is $3 but I'd like those paying with card to pay say, 3.22 while customers paying cash continue to pay $3. 

How could I easily do this? I think I'd have to kind of add sales tax to final price? (Right now it's included in that $3 coffee. )

Any help appreciated!

Thanks,

[straycatbrew]

You can make a button for the discount, leave it on the screen, and train your cashiers to press it before finalizing a cash transaction. 
You can’t do an automatic one, likely because a credit card company is not going to build a feature into their register discouraging a credit card transaction.

Make sure that this is legal in your particular state/area first. 

[MrJeezy]

Thanks Straycat! But how does one make a "discount" button?

[straycatbrew]

You can set up a discount under that tab (go to items, then choose discounts from the side menu instead of all items). You can add it to any of the POS screens the same as you would an item button. 

[MrJeezy]

Ah, thanks! I found it. It's odd how some actions are better on different versions. I found it on my iPhone version but could not on the desktop. 

So assuming it's legal in my state, I would basically raise prices around 3% across the board then have a 3% discount button to add manually for cash. 

Is there a way to automatically do this price raise across the board? Maybe with a tax function?