Belinda,
The only thing I can think of is a macro. You've got to open the macro editor which you can do by hitting Atl-F11 or use the tools, macro, visual basic editor option.
Once there, you should see a panel on your left that lists the names of the tabs in your file. If not, hit view, project explorer.
You should be able to spot the worksheet that you totals are on. Double click and you should see a blank window on the right which is where you're going to put the following macro.
Paste the following into that window.
Private Sub Worksheet_Change(ByVal Target As Range)
Dim mResult As Integer
msg = "total has reached " & Cells(7, 1)
If Cells(7, 1) > 10 Then
mResult = MsgBox(msg, vbOKOnly)
End If
End Sub
This assumes that the total cell is A7 -- that's referenced in the above macro by Cells(7,1) -- the 7 is for row 7 and the 1 is for column 1 (A). Obviously you can change this whatever you need.
Good luck.
Art