My partner doesn't lie over big things (I don't think) but he often lies to get himself out of trouble. We've had our fair arguments over him covering his tracks but he's definitely getting better.
But I seem to spot that he lies over little things but things he had no reason to lie about. I would have loads of examples but they're usually so little I end up forgetting but most recently:
Me: "Did you have a good day at work?"
DP: "I got a packet of 20 off Joel today, it's going to be my last packet as i'm giving up... it only cost me a fiver as they're duty frees.. I've set myself a challenge to make these 20 last as long as possible"
Me: "That's cheap. What are we doing for dinner?".
On a search for a phone charger I went in his laptop bag to find that he had actually got a sleeve of fags of 10 boxes (one missing for what I presume he was smoking).
I asked him how he had 10 packets when he had said one and he said they were so cheap it made sense. I sensed it was going for an argument and I can't be bothered. I accepted he was a smoker when we met so I can't fathom why he'd blatantly lie when starting a conversation.