Delta Air Lines has added a $5 surcharge for paying checked baggage fees at the airport instead of online, matching moves by some other airlines. Atlanta-based Delta already charges $15 for the first checked bag and $25 for the second checked bag on domestic flights. But starting Aug. 4, Delta will start charging those who pay for checked bags at airport ticket counters, kiosks and curbs $20 for the first checked bag and $30 for the second checked bag, for tickets purchased July 15 or later. The fees for paying for checked bags online remain the same.