Series to show % of Total and Cumulative % to Total?

Is it possible to create a series that shows the % of total of a row in a worksheet?

For instance, the following is desired:

Item     Revenue     % of Total

A         50                     32.3

B         75                     48.4           

C         30                     19.4

Sum   155

Another desired solution is how to show the cumulative % to total for items in a worksheet.  For instance the above data would show as:

Item     Revenue     Cum % of Total

B         75                     48.4

A         50                     80.7           

C         30                     100

Sum   155

This implies a different sort order of the items than the default 'alphabetical'.

Both are readily done in SQL, but can it be replicated in a Demantra worksheet?

Regards,

Bill