Obviously experience (in a related field) plays a big part in the latter rounds of the interview. But i believe grades are the criteria for making into the interview in the first place.
Having said that, i've been to quite a number of interviews myself. Quite frankly, some employers dont like people with experience (within the same sector) at all. (This is only true for more junior roles such as an assistant accountant). They think you have been screwed in the head from your previous job/s.
i believe in that theory because once you have started working you would have been taught to do stuff in a certain procdure. Then when the new employer employs you, he/she cant teach you the ways they want you to do things. i.e. it will be hard to change our habit of doing things.