I found some Russian site (maybe not Russian, but I can't read it anyway), that proposed this too.
This is not Russian, this is Finnish language.
I have an experience of ERP and POS developer. I programmed the extends for Openbravo and uniCenta POS during 7 years. Now I have a new open-source project NORD POS. My project source code based on Openbravo POS. I think interesting integrate support of bitcoin payments to NORD POS. But I think use Bitpay gateway SDK.