I am a little amazed at my results but it appears that 5mb/5min is about normal based on your amount of connections and client software. Here are the results from my testing:

The first test was 2 connections for 5 minutes and I transferred about 500Kb +/- 50Kb.

The second test was with 8 hosts and it consumed 3.5Mb/5min

The third test was with 3 connections to "Super Nodes" with 100Kb +/- 25Kb after 5 minutes.

If you don't have any extra bandwidth to "waste" I would suggest you limit the number of connections you keep to between 2 to 4. If you were to use a program that supports "Super Nodes" and you connected as a child (leaf) node your bandwidth would be reduced quite a bit.

PS - I am not sure if xolox supports supernodes so maybe someone could confirm it.