[jcousins]

The largest Bitcoin payment processor for retail is Bitpay, I've used them on a few websites. They enable shops to accept Bitcoin with a locked in exchange rate, shielding them from the volatility and the need to even hold and manage cryptocurrency. They charge a 1% settlement fee, which I believe is competitive compared to traditional payment processors.

Hard to say what proportion of transactions are retail driven, but Bitpay did write about their progress towards a $1B annual payment volume milestone recently[1] which is a drop in the ocean compared to the multi-billion dollar daily trade volumes on exchanges.

[1] https://blog.bitpay.com/bitpay-growth-2017/