We have two choices for the last digit, 0 or 5.  However the first
digit cannot be 0, so we must take the situations when 0 is the last
digit separate from the situations when 5 is the last digit.

1.  When 0 is the last digit:

We can choose the first digit any of these  6 ways {1,2,3,4,5,6}
We can then choose the middle digit any of 5 ways.

That's 6·5 or 30 ways.

2.  When 5 is the last digit:

We can choose the first digit any of these  5 ways {1,2,3,4,6}
We can then choose the middle digit any of 5 ways (since it can be 0).

That's 5·5 or 25 ways.

The total is 30+25 or 55 ways.

Edwin