Hi ya DD,
I dont know if there really is a perfect scale.. since you are reading 5lbs lost on each scale then I think you should focus on the fact that 5 are gone, not about how much the scale says you still have. Also, how about taking your measurements and going by how many inches you lose over time rather than what you weigh??

Weighing yourself can be discouraging since you sometimes retain more water than other times, and I find that if I weigh in on a morning that I am up in weight it can get me down for the rest of the day. Also, as you workout and gain muscle, you transform fat into muscle, and muscle weighs more than fat. Sometimes the scale numbers dont really represent the true picture.

hope this helps!
cheers,
Jodi