See response below

In Odoo 17, you can handle the scenario where the vendor provides a fixed quote for a requested product quantity by utilizing the "Fixed Price" feature in the Purchase Order. Here's how you can address this issue:

1. Create a Purchase Order:
   • Navigate to the Purchase app.
   • Create a new Purchase Order for the desired vendor and product.
2. Add Product:
   • Add the product to the Purchase Order line.
3. Set Fixed Price:
   • In the Purchase Order line item, click on the 'Unit Price' field.
   • Select the "Fixed Price" option from the dropdown menu.
   • Enter the fixed price provided by the vendor.
4. Adjust Quantity (if needed):
   • If the requested quantity varies from the vendor's quote, adjust the quantity accordingly on the Purchase Order line item.
5. Verify Total Amount:
   • Verify that the total amount on the Purchase Order reflects the fixed quote provided by the vendor.
6. Create Invoice:
   • When you receive the bill from the vendor, create an invoice based on the Purchase Order.
7. Match Invoice:
   • Match the invoice with the corresponding Purchase Order to ensure accuracy.

By using the "Fixed Price" option in the Purchase Order, you can accurately reflect the vendor's fixed quote and avoid rounding issues with fractional unit prices. This approach ensures consistency between the Purchase Order and the invoice, allowing for accurate billing based on the vendor's quote.

I think it was the same in V14, that you only can change the unit price. There is a reason for this for calculation of product cost, I think. (FIFO and AVCO cost, use the unit price for calculation

What we do: Product are measured in Kilos og Meter, we purchase and sell in Tons and Kilometer.  Then the price is more accurate.

Even then it not always match. In the vendor bill we add a line with the correction, so the total bill value matches. I

It is not perfect solution, but the discrepancies are acceptable.