The idea of a penny rolling around gives the idea of it being aimless and out of control to an extent, which is a metaphor for how she is feeling ‘inside’ with regard to her life and relationships. The ‘penny rolling up the walls’ signifies her unstable emotional state. If the penny rolls up, it has to roll back down. Which may also signify the up and down highs and lows that you have when you take drugs. “Life is like a pipe” refers to being stuck in a round object and looking down the end. It’s dark and you can perhaps see a small amount of light at the end of the tunnel, however you can’t escape. This is a metaphor for the misery she feels. Also with a pipe you can smoke pot and different drugs.
If anything, feeling like a tiny penny rolling up the walls reveals a feeling of an utter lack of control—being a tiny penny reflects her feeling of near insignificance in terms of her power when it comes to this man who tosses her to the side at his whim.