lol, i wish that was 6% of my salary, I'm a dirtypoor
Dude, then this conversation is EASY.
"Boss, I need x percent raise. Cost of living goes up 2-3% a year and it's been y years since my last raise. If I don't get a raise in essence I'm losing money to work for you."
Done and done. Even if you don't take this tact, it's all the more important to not talk about dollars, but percentages. A boss will think "Where am I going to get 10k from?" But might think "3% isn't that bad...."