a pound cake might get 5" deep--but that's a thick slab of baked goods--it would be baked in a tube pan though--hole in the middle otherwise it could hardly bake through
but you could layer shorter cakes with icing in between to get it 5" deep
The deepest cake tins are angel food tins at 4"deep.
Do you have a 5" deep (top to bottom) tin? Why not make layers?