DeskAdder
Treat it as a digital adding machine as opposed to a calculator. There is a difference. Feel free to report bugs or request enhancements and I'll look at them right away. A help file is available with some basic information(it's just an adding machine). I've listed some of the keyboard shortcuts below the screenary.
DeskAdder version updates can be seen here.

|
ESC = Exit |
s = Subtotal |
g = GT |
e = Correct entry |
|
Enter = Total/= |
c = Clear |
0~9 = Numpad 0~9 |
a = Average |
|
F3 = Decimal left |
F4 = Decimal right |
d = Delta % |
u = Mark up/down |
|
F5 = M+ |
F6 = M- |
F7 = MS |
F8 = MT |
Your number pad works as you might expect.