Hello @CC99 thanks for your post. Do you have inserted anywhere in your items the cost of the item? Or do you just have the retail sale price listed? If you have the cost (perhaps you track "cost of goods sold"?) for each item, I don't think you can create a dynamic or changing discount that will auto-calculated and then apply this discount.
However, you can manually add sale prices to each item, but you have to go into your Square Dashboard, and into each item and add your sale price. You'll have to know what your cost per item would be so you can manually add them. See the screen shot below for an example on where to click to add your sale price. Note, the sale price would show up and be available to anyone shopping on your website; you cannot have this be used as a discount that would be entered into as a coupon type of code.
