It honestly doesn't matter much. Numbers given on a resume or during an interview are not binding in any way. They are just there to stop wasting people's times if expectations are wildly different between the company and the potential employee. If you are really worried about it, just say the salary must make the job switch worth it to you (meaning you won't take what you are earning now).
The only time that the numbers actually matter is when the job is offered to you. Then the prospective employee has their best upper hand. The company just did an extensive job search, maybe taking months, often costing thousands of dollars, desperately needs the job done, and really likes you. Any number given up to that point can be tossed out. Let them offer you a job with a specific salary offer and you negotiate from there with a position of power. You could have said $50k in the interview and counter offer with $80k once they offer the job, because the $50k is non-binding (the person offering the job often is different than the person that you said $50k to anyways and doesn't even know what you said).
Obviously you can't counter offer with something astronomical and expect to get the job. But you can certainly negotiate.