The Red Devils are believed to have had an opening offer of £67m knocked back for the England international last week.
Sport1 journalist Patrick Berger claims that BVB are holding out for closer to £77.4m, which United are likely to match in order to bring the transfer saga to an end.
However, it has been suggested that United must also agree to pay off that full amount over the next three or four seasons, as opposed to the five years they previously proposed.
Dortmund are proving tough negotiators and will supposedly not budge on their demands, leaving the ball in United's court in the long-running saga.
Sancho, currently away on Euro 2020 duty with England, has scored 50 goals and registered 64 assists in 137 outings for Dortmund in all competitions. body check tags ::