Vietcombank sold the dollar at VND23,650, up 0.13% from Thursday.
Eximbank and Techcombank kept their rates stable at VND23,600 and VND23,610, respectively.
The State Bank of Vietnam raised its reference rate by 0.07% to VND23,672.
Unofficial exchange points sold the greenback at VND23,450, down 0.09%.
The dollar has dropped against the dong by 0.34% since the beginning of the year.
Globally the dollar firmed near a six-month peak against the yen on Friday on the back of rising U.S. Treasury yields, as optimism over debt ceiling talks in Washington raised expectations of higher-for-longer interest rates, Reuters reported.
The U.S. dollar index was last at 103.46, flirting with Thursday’s two-month high of 103.63, and was headed for a second straight weekly gain of more than 0.7%.
"Optimism about the debt ceiling (talks) has contributed to a repricing for the Fed ... the fact that (a deal) would remove a big weight on the economy, effectively," said Ray Attrill, head of FX strategy at National Australia Bank (NAB).
"It does remove one obstacle to the Fed continuing to raise rates."