In reply to mann:
This still does not make much sense. If every transaction has a queue of arbitrary size, how do you expect to get toggle coverage for the transaction with the largest queue size? Unless the queue size is not as arbitrary as you say it is. In that case you will have to create an array of covergroup instances to cover each bit as described in this post. You will need to iterate over each bit over each queue element. This will be a very expensive operation so consider if this is really necessary.