T.P.
M.,
My son is 12, and also has a problem with telling the truth. For him it is on a daily basis about just about anything. I have noticed that with him, sometimes he will respond to a question without thinking threw the answer. He realizes that he has not told the truth, or just given the wrong answer,and would rather lie than admit he is wrong. Other times my son will lie for the attention. I have 4 children ages 13, 12, 10 and 16 months, and there are times when Mom and Dad are both busy and that is one way to grab our attention.
Your son is a few years younger than my son, so there may be very differant reasons he does it. I hope I have helped. :)