Yes, if the kinetic energy (i.e. the round's mass times the square of its velocity) of the discharged round equals the kinetic energy of the falling tank. Otherwise no.

If it were true, if the round's mass times the square of its velocity equaled the KE of the falling tank, the tank would stop in the air, then resume its fall as though from a stationary start.

And ... the sudden stop would probably kill the tank's occupants, just as though it had collided with the ground.