[PeterisP]

Can you give an example of how the heck an EMV transaction could require 5 round trips ?

IIRC it should come down to 0 or 1 roundtrips, depending on the amount and risk profile - in most cases you do an offline authorization where only the chip is involved to verify the txn, PIN(if applicable) and limits; and if you can't do that, then you send an online authorization, get a response, and that's it. There's extra communication afterwards in the workflow, but that happens after the customer has left and has no impact on customer-observed latency.