I think it has to do with dimensions. Now, your expressions are presented per dimension. For each dimension, there is a Last(?) and Total expression. I can imagine that you can achieve the excel layout by using a dimension that contains all your previous dimension units.
Did it help? With a sample qvw I could give you a better answer.
I think what you need here is a handy thing called ValueList(). This allows you to create a synthetic dimension which you can then use to define two different expressions on the same axis. Here is my example built using ValueList().
As we are creating a synthetic dimension the "Relative" tickbox won't quite work right so you will need to use a bit of set analysis to define the total sales to compare against and give you a nice percentage. The dimensions and expression I used are: