Shopify POS interface customization

Job ID: 31834611

Budget: $250 – $750 CAD

I need a customization for my shopify POS interface. I sell lotto tickets in my store and other products also. Sometimes I need to pay my customers lotto winning prize (cash out of my cash-drawer) when they win with their lotto tickets. I need 2 things :
1 - A tile in my shopify POS called "LOTTO" for which I can put any amount for the lotto ticket that I sell. It is a variable amount that I will enter manually for each customer. This LOTTO product has to be added to the cart as a regular non taxable product.
2- Another tile in my shopify POS called "REFUND" in which I can put the winning prize and this has to be added to my customer cart as a "negative" sale. Besides this refund amount is a non taxable item.
Example : 1 customer wins 100$ and buys for 50$ of other products in my store. I want it to be reflected in the cart as
REFUND -100$ (Non taxable)
Product 50$ (+ Tax of 10% for example)
Taxes 5$
Total = -45$
As you can see sometimes I owe money to the customers but sometimes they owe me money when their winning prize is lower than the products they buy in my store.
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