FWIW, I'm not convinced this would raise soda prices even a bit. Coke and Pepsi may be forced to eat the entire tax. Their prices have largely been unchanged since I was a kid, so their markup is already huge. If Coke raises the price but Pepsi doesn't, they'll lose revenues. And there will be reason for both not to move up.
When you make a good profit margin, it's hard to pass on the tax (if you could, you'd already be charging more to begin with).