When I use Physics2D collider, Bounciness of 1 is slightly wrong.

I have started a "Breakout" clone, and when I put the appropriate colliders on (with default values), and a Physics2D material on the ball with Friction = 0 and Bounciness = 1, the ball bounces higher and higher each time for some reason.

Has anyone ever experienced this, and found a way (other than setting bounciness to .9725) to fix it?