As a Daemon player who frequently uses deep striking tactics, I would say sentinels wouldn't really help. If your opponant really wants to take down your tank he can ignore your sentinels pretty easily or, if it is a kill point game, you have just given them some easy points.
I have a friend who plays an armoured brigade army; his tactic when I deep strike units is to:
a) Spread his tanks out as much as possible so I can't get the turn after turn chain kills.
b) Target one unit at a time so that he has less tanks going down each turn, even if he does have to deal with stronger targets next turn.
c) Use psychic powers on the tanks that he doesn't want to lose so that I am less likely to charge them.
Hope that helps