How to design the heuristic for A* when there are multiple goals in the grid map?

How to design the heuristic for A* when there are multiple goals in the
grid map?

I am facing a problem that I have to use A* to search through the map, and
there are multiple goals in this map to reach. My aim is to expand the
least nodes in the map, any idea on how to design the heuristic for this
A* algorithm? thanks