I owe a bunch of parking tickets and a registration fee to the dmv. Can I discharge this in a chapter 7 bankruptcy?
I think no. A parking ticket is a "fine, penalty, or forfeiture" that would be non-dischargeable under 523(a)(7). If you owe money to the DMV for a registration fee, I suppose you could discharge that in bankruptcy. But then you wouldn't be able to renew the registration, either -- this is a fee for a service. You can't get the service if you don't pay the fee.
You didn't ask about it, but you CAN force the DMV to renew your license or registration if the only thing holding it up is the unpaid parking tickets. (At least here in MA you can.)