How much does it cost the merchant to accept cash?

It takes time to count notes and coins, and to give back change.
Counterfeits might be a problem.
Money needs to be counted at the end of the day, which takes time.
Employees may steal a little a bit as the sum seldom adds up anyway.
Money needs to be transported to the bank securely, which isn't cheap.
Cash pays no interest until deposited in bank.
Other costs as well?
How much does this all add up to?

My local supermarket has a lcd monitor at each counter where it shows the price (among other info). It could very easily also display a bitcoin QR code. Assuming zero confirmations is secure enough, it would take only seconds to make a payment. The supermarket could exchange bitcoins to euros several times a day, and only face fees and spread which adds up to 1% or so. Would a payment in bitcoin be more lucrative for the supermarket than cash?