It is mind boggling that the chart and matrix views of a report do not allow you to sort by the grand total!
These chart & matrix views should allow you to define a sort order.
For the chart, you should be able to sort by the total, or the label (ascending or descending) or a value that isn't displayed on the chart.
For the Matrix view, you should be able to sort both dimensions. Either by the label, or the total.