You don't say if the 5 includes you or not, so you might save 5 people but die yourself!
My first thought was to save my family, but then I wondered if we would really want to survive alone on a planet with nothing else on it. If everything is destroyed you would be scrabbling in the dirt for food or shelter. If your loved ones didn't die from starvation or illness, you'd have to watch them die from loneliness. Your children cannot have lovers or children, unless they have an incestuous relationship which would then lead to deformities in their offspring.
I think that would be a horrible life to condemn someone to.
If the world is to be obliterated I would rather hold my loved ones in my arms, telling them I love them, as we all evaporate together.
The 5 I would leave would all be world leaders, probably George W. Bush, Russian President Vladimir Putin, Chinese President Hu Jintao, French President Nicolas Sarkozy and any one of the recent British Prime Ministers, probably David Cameron...or better yet, Margaret Thatcher.
Let them live together without their spin-doctors and their sycophants. See how long they survive. See if they could actually survive rather than just pay lip-service to their ideals.