(ETA: oops, just realized this is in the 20-something section, and I am not.
Please forgive the intrusion, and I hope the comments are helpful anyhow.)
All of this is why I use a scale that only reads three digits, and why I just don't fret that much about fluctuations of a pound in either direction. I do weigh every day, but I don't really consider it a "gain" if I read a pound higher today than yesterday, or a pound higher now than an hour ago. I don't look for progress day-to-day - the time scale for meaningful weight change is longer than that. It just is.
0.2 or 0.4 pounds is a really meaninglessly small amount - I can take off my glasses and change my weight by that much - and it's not really a huge surprise to me that the cheap gauges that they put in inexpensive household scales don't return repeatable measurements at that level.
So, I know it's hard, but try not to let the scale ruin your mood at the level of changes of less than a pound or so. Get used to your measurements being really a bit less precise than the digital readout makes it seem. Look at long term trends - not a day, not even a week, but weeks and months - as your gauges of success.