this looks like it works - Thanks!
it is so simple yet i cannot figure out how and why it works.
could you briefly walk me thru your steps.
So all I have done is to create a normal Tableau group, to group the two red-cross values together. Then,instead of using Tableau's bins (which work out which bin each individual row in the underlying datasource falls into) I have defined a calculated field which works out the total for each group member before calculating which bin it falls into.
So the SUM([amount]) gives you the total for each group member (as long as you have the group on the view somewhere), and then the expression:
is working out the bins (divide by 100, take the integer part and then multiply by 100 again).
If you actually have more dimensions in play (such as a time period, for example) you will need to think carefully about what level of aggregation the SUM() is giving you. You might even need table calculations to get the degree of control you need if that is the case.