Partial refunds must always be sent VAT-exclusive. Whether you use feeds (XML or Flat files) or Seller Central, you must send VAT-exclusive prices. Amazon uses the VAT rate that was applied for the original shipment and calculate the VAT based on the VAT-exclusive price. For example, if the VAT is 20% and the item cost was €240 (€200 + €40 VAT@20%), and you want to refund 50% (€120) then you need to provide €100 in the Product field and Amazon will add the VAT (€20), ensuring that the customer gets €120. Do not input any value in the Product Tax field. Amazon will ignore it. The same applies to Shipping and Gift Wrap.
Updated about 1 year ago