how to compute totals grouped by field?

[Adam Dingle <adam medovina org>]

In Gnumeric, suppose that I have a series of rows representing payments 
to vendors.  Each row contains a date, a vendor name and a payment:

4/3   XyzCo   4.15
4/4   AbcCo   8.20
4/5   XyzCo   2.25
....


I'd like to construct a table showing each vendor and the total of all 
payments ever made to that vendor:

XyzCo  6.40
AbcCo  8.20
...


Is this possible in Gnumeric?  Or must I export to an SQL database and 
execute a query such as 'select sum(payment) GROUP BY vendor', which 
would have a similar effect?

adam