Can you counter a counter offer?

I know you can submit a counter offer to a seller's counter-offer, but is it considered rude to do so? Or is it considered normal to haggle / negotiate? Sorry if this seems like a silly question, and I want this laptop. But I don't want to piss off the seller, and I feel they may not take me seriously and just hit 'decline' to my offer. I do still feel like I have a bit of room to negotiate. Thanks for looking...