U can do it if 101 and 102 belong to another hierarchy like 100 and 201,202,203 belongs to the 200 in the same level. I mean if u have data as below.
If u don't have hierarchy as shown try to create one with some business logics, since u look interested in summing 101,102 and 201,202,203. If u don't have such level then I thinks its hard.
Once u have that level created u have the option in presentation tab. otherwise I guess it is not possible in Pivot table.