Yes, that's possible. It depends on your data what kind of trickery you need to resort to. It might be enough to set the sorting of each dimension to Custom, enable the Sort by expression option and use sum(Sales) as expression. That works for data sets like
Dim1 Dim2 Dim 3 Sales A R X 100 A S Y 200 A S Z 300 B K F 50 B K G 75 B L H 100 C M Q 125
But if you have something like
Dim1 Dim2 Dim 3 Sales A R X 550 A S Y 200 A S Z 300 B R X 50 B S G 75 B S Z 100 C M Z 125
then you probably have to resort to calculated dimensions like dual(Dim2, aggr(sum(Sales),Dim1,Dim2) for Dim2. Then you can sort that calculated dimension with Sort Numerically.
Unfortunately the pivot table has no Sort by Y-value like previous versions of Qlikview had.