How much do you think the price of a sandwich at McD will rise when the minumum wage goes to $15 per hour?

Does anyone have real numbers?
I will make an engineering estimate here so please criticize and adjust my numbers. This is engineering so I am not offended if you do it a different way and come up with a different result. We are crowdsourcing.
Imagine a McD. I will assume in one line they handle one customer per minute. Some are faster some are slower. I’ll say a typical order is 2 sandwiches on average. So one register is doing 120 sandwiches per hour. There are 4 registers running so let’s call it 500 sandwiches per hour. How many employees are there? 4 cashiers,. 4 cooks, 2 support = 10 people Assume they earn $10 now and it will go up to $15. That means it will cost an additional $50 for those 500 sandwiches or 10 cents more. A Big Sac would increase from $3.59 to $3.69 (without hurting the salary and bonus of the big boys getting paid over $37 million per year.) Would that 10 cents affect your normal McD eating habits?
Sure, my example is for peak lunch hour. At off peak times there are fewer registers running, fewer employees cooking and supporting, so I figure my estimate is still reasonably close.

How much do you think the price will increase? (Will the big boys double the increase and use it as an excuse to increase their bonuses?)