Seeing whole lot of decimals in value

[CptMeatmug]

First of all, thanks for your work!
My issue is that I'm experiencing way too many decimals in value, as the image shows:

I believe this has something to do with floats, round-off error or such. After several hours of googling, I wasn't able to do the rounding in HA, so I ended up adding round( ) to sensor.py (line 158)
return round(sum((w['waterconsumption'] for w in self._withdrawals if w['starttime'] >= since)),1)