As a rule of thumb, you should dress for the interview the way you would for the job itself. (If the job is unusually casual, however, you might want to show up in business-casual clothes to be safe.)

If you're unsure of the customary interview clothing expected by the company, simply ask the HR rep or interview liaison. There's no shame in it. There is shame in feeling horribly over- or under-dressed when you show up for an interview.