Use DECIMALfor exact values.
The number 0.00001has 6 digits. 1 before and 5 after the decimal point. Therefore, it will be represented as DECIMAL(6, 5)(6 digits, 5 of which are after the decimal point). If you want to have, say, 4 digits before and 5 digits after the decimal point, you should use DECIMAL(9, 5)(total 9, of which 5 are after the decimal point).
See also: