Yes, Congress should absolutely return at LEAST 5 percent of their salaries to the Treasury. The reason why the sequester passed is because of Congress. They are why we are facing so many spending cuts. Congress got us into this mess because of their laziness and childishness and stubbornness. Congress should get us OUT of this mess.
Congress already has high paying salaries, along with the massive amounts of money they get from their corporate donors. And who cares if it is only a symbolic gesture from the president? Maybe some symbolism from congress that we're all in this together is just what this country needs. I feel as if an act like that from congress if they all voluntarily gave up 5 percent of their income would show to the American population that this is an American problem, not a middle class problem.
Obama is only doing this as a symbolic gesture to help himself out politically. He is already a millionaire and therefore can afford to spare his government salary that he does not even need. Congressmen are not all rich and a lot of them cannot afford to give away more of their money (they already pay a crap ton in taxes, thanks liberals...)
If you look at the big picture, Congress returning 5% of their salary will not have an effect on the deficit or anything else important. Maybe it is the principle of them doing so that would count, but it doesn't really bother me. I don't approve of Congress, but I don't think that is necessary.