The State Bank of Vietnam set the daily reference exchange rate at 23,166 VND per USD on August 4. (Photo: VNA) Hanoi (VNA) - The State Bank of Vietnam set the daily reference exchange rate at 23,166 VND per USD on August 4, down 10 VND from the previous day. With the current trading band of +/- 3 percent, the ceiling rate applied to commercial banks during the day is 23,862 VND/USD and the floor rate is 22,470 VND/USD. The rates listed at major commercial banks saw fluctuations. At 8:30 am, Vietcombank listed the buying rate at 22,810 VND/USD and the selling rate at 23,040 VND/USD, both down 5 VND from