Tangled reads Square's Item Sales Detail CSV as it is.
Square Service rows count as service sales, product rows as retail, and refunds are subtracted. Tips are not in this file.
Steps from Square's Support Center (Item sales reports) and Square Community answers on exporting the Item Sales Detail CSV. Square has moved these menus before; if yours look different, look for Item sales under Reports.
Your data stays yours. Files only; nothing connects to your POS.