I struggled with this too, can’t remember exactly how I fixed it will have to dig through my github to find the fix for my devices. But all my temp sensors report and display tenths of a degree.
I think the trick was to change the display type to a string / text and keep a state var for the decimal value.
I think I even had a rant a few months back on the rounding (or truncating) the default devicetypes were doing… So I feel your pain… Been there, done that, fixed it myself, shared the code… But really can’t go much further…
Just for a few searchable references for this issue.