I Had A Tetanus Shot About 3 Years Ago...I Was

I had a tetanus shot about 3 years ago...I was told that if I got a cut that the shot would reduce down to 5 years until i needed the next shot. UNLESS I got cut again and then I would need to go in and get one. I was just cut on the arm from an old barbwire fence. Do you recommend I got get a tetanus shot booster?