Take each piece and divide it into 5 smaller pieces. You will then have 40 small pieces. Give each of the 5 people 8 small pieces.
Another (less fiddly) way is to give each of the 5 people a whole liquorice piece so you are left with 3 whole pieces. Divide each of these into 5 smaller pieces so you have 15 small pieces. Give each person 3 of these. Each person will then have a whole piece and 3 small pieces.