Do you mean you want a group by?
SELECT
Tag
,sum(QTY)
,sum(Price_Of_Unit)
FROM
Table
GROUP BY
Tag
This will "group" all rows with the same tag, the other columns are functions on the group of rows - here i have chosen sum which adds together all the QTY and Price_Of_Unit columns.
Group By:
http://office.microsoft.com/en-gb/access-help/group-by-clause-HA001231482.aspx
you can do other "aggregate" functions instead of sum:
http://msdn.microsoft.com/en-us/library/office/bb177686(v=office.12).aspx