I can't use all 10 digits here!

Logic Level 1

$\begin{array}{ccccc} & & & \square & \square &\square \\ & & & \square & \square &\square \\ + & & & \square & \square&\square\\ \hline & & 2 & 5 & 5&5 \end{array}$

The above is a long addition with some numbers hidden in the boxes. Each box represents a distinct digit from 0 to 9.

Fill up all the boxes and find the digit not used.