Sorry for resurrecting an old thread but I think this is not that stupid after all (not an elegant solution either, I admit).

As far as I understand, an implementation of niko's solution would be to maintain a list of 50 addresses of 0.01 BTC in each one of them (generated at home), and give the required number
of them in the form of QR codes to the seller (who typically is a brick-and-mortar with internet connection) . Assuming that

1. there are no problems with network fees

and

2. rounding error of <1$ is acceptable to either the seller and the buyer

this would work nicely