On all the images that TP-Link use for advertising the Tapo T315 it shows the temperature as 25.0°C and the relative humidity as 53.0%.  In the Tapo App, if you click on Tips for the T315, it shows diagrams with the humidity as 36.6%.

This implies to me that you should be able to get a relative humidity reading to 1 decimal place of accuracy.  All my humidity readings, however, are shown as whole numbers followed by "point zero", so please can someone explain how I get the app or the device to show a tenths digit other than zero after the decimal point.  I appreciate that a change of 0.1% on the relative humidity scale is negligible, but given that in the tips it shows these images, it must surely be possible.