Decimals in temperature application

This is the part of my code that check the temptrature of the DS18B20 and send to blynk.
I do get one decimal, but it is only rounded to “.5”; like 16.0 16.5 or 17. I Never get 16.1 16.2 and so on. I guess I use the wrong data types?;
      sensors.requestTemperatures(); // Send the command to get temperatures
      Blynk.virtualWrite(V1, sensors.getTempCByIndex(0));

I think this is not a problem of data type. Kindly consult the DS18B20 datasheet. You need to configure it for the required resolution of 0.5, 0.25, 0.125 & 0.0625 degrees Celsius.