I've been in the wedding business for 15 years and I get this question all the time: "Should I tip the musicians?" The answer is simple - if you are happy with the service you received and feel like musicians deserve the tip, Do it. Just Do it. You will feel better about yourself, and we will appreciate your generosity.
Although the protocol for the gratitude is optional, we always appreciate a tip. No matter the size. How much you should tip depends on your budget, but industry standard is 15 percent. It works out to be around $15 - $20 per musician.