Can you give an example:

1234,
is entered as text for me
or
123.00
reverts to 123
(excel sees the value of the cell and 123=123.00)

But if I type:
$1,234.00
excel will see the value as 1234 (in the formula bar) and keep the formatting
for you, too.

John Z. wrote:

When entering data into a cell, particularly a four digit number followed by
a comma, and three digit dollar figure with a decimal point and no cents, the
numerals change format into a single number with commas.

--

Dave Peterson