Surrender or hit A,5 against dealer 10?

If a casino offers surrender, 16 v 10 should be surrendered right? But what if that 16 is comprised of A,5? Do you follow the Soft hand rule of hit, or the surrender rule? My logic tells me surrender, but then again, my logic has gotten me in trouble in the past :_)

Incidentally I have seen varying numbers in percent on the advantage of surrender. In Foxwoods, in a 8 deck game, DAS, double any card, S17, what does surrender offer in percent? Thanks.