Solana NFT Trade Transaction Identification

Question

I am trying to identify which Solana transactions are actually NFT sales. I am using Solana JSON RPC to get the information about the individual transactions but I cannot figure out from the data what is an actual sale. For example this NFT token is marked as 3 Trades: https://solscan.io/token/7N6AxAxtPijknC7bRtfi5EpiwELN4Dsj4BhZqHvAXFmR#trades

But has numerous transactions associated with it: https://solscan.io/token/7N6AxAxtPijknC7bRtfi5EpiwELN4Dsj4BhZqHvAXFmR#txs

All of them are marked as SPL Token transfer.

So how do you know which one is an actual NFT sale? Is that via message logs in the transaction, via the account information? Looking at the Post and Pre Token balances it is also not clear even if the owners and account indexes are different sometimes transaction is also not considered a sale.

Any hints?

Many thanks for help in advance.