Step 1 — Create a supplier
Go to Cost & Margin → Suppliers. Enter a name, the currency (e.g. EUR if the supplier invoices in euros) and an optional FX buffer percentage. The buffer is applied to the exchange rate in the calculation — it protects your margin against rate movements and never ends up in COGS.
Step 2 — Set your rule
Under Rules you find a global default rule. Choose margin or markup, enter the percentage and pick a rounding — e.g. "end on 9" so 187.43 becomes 189. In Pro you can add rules per category, supplier or product; the most specific one wins.
Step 3 — Give your products a cost
Either directly on the product page (the Cost & Margin tab) or via import: upload the supplier's price list under Import, map the columns once (the mapping is saved per supplier) and review the matches. The cost in your store currency is always written to WooCommerce core's COGS field.
Step 4 — Run and review
Go to Price runs → Preview. You see every product with old price, new price, real margin and the full calculation. Apply when you are happy — and undo with one click if something went wrong. Next time the price list arrives, this is the only step needed after the upload.