It's unlikely that jQuery will help you if you never do anything with web front ends. If you're 100% server-side, then there's little point in learning jQuery (arguments about "learning for its own sake is always good for you", the elegance of its design and implementation, prototype programming ideas aside).
If you do web UI work, it's hard to see how you can miss out on learning jQuery. It's become the standard JavaScript library. If you browse this site for very long, you'll see that lots of JavaScript questions are answered with "Use jQuery".
It reminds me of a quote from Louis Armstrong about jazz: "If you've gotta ask, you'll never know." You shouldn't have to come to Stackoverflow to ask whether you should learn jQuery or not.