With every transaction on the XRP Ledger, a small amount of XRP is destroyed, or “burned,” as a transaction fee. The minimum cost required for a standard transaction is 0.00001 XRP, or 10 “drops” (the smallest unit of XRP). 
This mechanism aims to protect the network from spam by making attacks expensive. During periods of high network activity, these fees can increase to maintain the efficiency and security of transactions. 
It is important to note that these fees are fixed per transaction and do not depend on the amount transferred. As such, the percentage of XRP burned per transaction is usually very small, if not negligible, compared to the total amount of the transaction.