I would like to simply create a keyboard shortcut for some of the
toolbar buttons, namely the "Increase/Decrease Decimal" buttons.

I tried just recording them, but it records the action specific to the
recorded cell, -- i.e. if the cell that I record using the "Increase
Decimal" button on has 2 digits to the right of the decimal, the macro
will record

Selection.NumberFormat = "0.000"

The problem is, this recorded macro will set the number format to
three decimals, no matter how many decimal places are currently
displayed. I could do a workaround using if then statements, but this
made me wonder how I could either view the code that the toolbar
buttons use, or just assign a keyboard shortcut to existing toolbar
buttons.

Any ideas?