Correct number of decimal places in form

[amn7940]

I want to check to see if a user entered the correct number of decimal points. In the database the amount is DECIMAL(4,2) . How would I enforce this?
Acceptable input:
1
1.1
1.11
11.11

[NogDog]

One option would be to simply force it:

$value = round($value, 2);

If you want to validate it, one possibility would be:

$value = trim($value);
if(preg_match('/^\d+(\.\d{1,2})?$/', $value)
{
   // valid
}
else
{
   // NOT valid
}