MONETARY data type is an approximate numeric data type. Representable range is the same as FLOAT, which is represented to two decimal places; the representable range can be different based on system. A comma is appended to every 1000th place.
You can use a dollar sign or a decimal point, but a comma is not allowed.
If you specify 12345.67898934 as MONETARY, $12,345.68 is stored (it is rounded to third decimal place).
If you specify 123456789 as MONETARY, $123,456.789.00 is stored.