Google is your friend.
"In general, McDonald's franchisees pay about 20 percent in labor costs, according to Richard Adams, a consultant out of San Diego who works with McDonald's operators."
Of course, this varies widely from industry to industry. For example, in hotels (which also have a large number of minimum-wage workers) "...in 2013, labor costs represented 32.3 percent of total revenue".
It's impossible to calculate what raising the cost of labor will do to the cost of the product to consumers, because supply and demand drive that more than anything. You can *assume* that all other production costs remain fixed and that use of labor remains unchanged (however unlikely that is) and that the extra labor costs are passed directly to consumers. But surely everyone realizes how unrealistic those assumptions are.
One thing that is clear, though, is increasing the cost of labor will certainly lead employers to look at ways to reduce labor costs, with technology and automation leading the way. I image that soon we will not need minimum wage workers at McDonalds because we will have self-serve kiosks with touch screens and Siri-like voice ordering sending our orders to a McRobot that assembles all orders with extreme precision (no wrong orders!). One on-site "food engineer" can service the robot, and one "manager" can provide security and resolve the (hopefully) rare complaint about the robotic system. He or she, of course, will not be a minimum wage worker, as servicing the robot will require extensive training.
We already pump our own gas, ring up and bag our own groceries, etc. as technology reduces labor costs.