How much lying is *too* much? Everyone fudges the truth sometimes, but some people are habitual liars! Should?

I trust my guy? He lied to a store ociate and said he had to leave and get lunch. But he wasn't going out to lunch but he just didn't want to talk to the ociate anymore. It seems so small, so why lie?! Then he lies to his job about his days off. THEN someone called his cell at midnight and I asked who it was. He said he thinks it was his friend Terrence (I knew it wasn't). I asked again and then he checked his phone and said it was his friend Sabrina! OK, they both work nights, so they're usually up at that time. But I think he lied again. Are these small things or should I not trust him?