How to get accurate temperature readings from DHT11 sensor?

I am using DHT11 with GrovePi+ on Raspberry Pi 2 and using code provided on github for DHT11

However it returns the readings only before the decimal. Values after the decimal are truncated to 0. Eg. 22.0, 34.0, 10.0
How to get the accurate readings from DHT11?

Is is Possible with DHT11? or Do I have to purchase DHT22?