What should I do if I come across a PHQ-9 score with a decimal point such as 2.5? Should I leave the score blank or enter the score as a 2? 

The scoring of the tool is meant to only be whole scores so to have a decimal score, invalidates the tool. I would communicate to staff that if it is noticed that a patient circled in between two numbers or did anything else to indicate a decimal, that the patient should be encouraged to select a whole number.