Turn him in, you can never be absolutely 100% sure it was him unless you saw his face, so there should be no guilt there, just report what you saw. You also have to think of the store owner, people like to think of companies as deserving victims, but in all likelihood a salon is run by a small business owner, a person with mortgages, kids, bills and all kinds of things, the last thing he/she needs is some idiot smashing a window and robbing them. Even if they have insurance and the damage gets covered, their premium will go up, and in the end they are a victim twice. Not to mention piece of mind, just imagine being that store owner tomorrow and seeing what was done and wondering who would do this to you and why, and imagine at least the relief and satisfaction knowing the person was caught and it wouldn't happen again.
The one thing we should all be able to agree on is that crime is bad, in all manners. Look at your options, do nothing, crime continues as usual, say something, at least one criminal thinks twice next time or is off the streets.