Heinens would be great, and in fact we have already spoken with another grocery store in the area. But, we are still uncovering a lot of logistical issues for a store this size. There is simply not tight enough POS integration today to do this quickly and without development costs. Bitcoin revenues are so low right now, that investing in development is not something that has an ROI worth considering.
For instance, this issue also affects restaurants. Many of them use Micros POS systems. To even begin talking with Micros for a custom native integration is $15,000, and that does not include actually doing the work.
My hope is that the "bigs" (BitPay, Coinbase) will work with POS vendors to attain native integrations. Once this happens, it will be faaaar easier to approach larger organizations.
I wonder how much work would be involved in taking one of the existing open-source POS systems (UniCenta or Softaculous for example) to incorporate crypto-payments?