NEW YORK (Reuters) - The euro gained against the dollar on Friday for the second day after the European Central Bank on Thursday exempted euro zone banks from a penalty charge, which analysts say will reduce the currency impact of new stimulus.The ECB on Thursday cut its deposit rate to a record low -0.5% from -0.4% and said it will restart bond purchases of 20 billion euros a month from November. The purchases will run for as long as necessary and end shortly before it starts raising the key..