Found it (Thanks JayDee116!)
On page 4 of the "Operator's manual" (
here, PDF, 14 pages), it states:
General Specifications to all chillers
-Temperature setability +/- 0.1 deg C
-Temperature uniformity +/- 0.5 deg C
...
So the temp may fluctuate up and down by as much as 0.5 degrees C.