I got a question regarding multi-clas and hitpoints. I got a dwarf fighter-cleric. He got a Constitution of 19. This is how I think it works, please correct me if I am wrong. When he levels up as a fighter he gets D10/2 hitpoints(1-5) and when he levels up as a cleric he gets D10/2(1-3) hitpoints. But what about the constitution bonus? How do you divide 5 with 2 and get an even number? Do they round up or down, or how does it work? Any help would be greatly appreciated. Thank you.

a multiclass cleric gets d8/2 (1-4) Hp pr. lvl

IIRC the CON-bonus is rounded down

I think this is how it works...
Fighter level (1d10+5) / 2
Cleric level (1d8+2) /2

Shadowpup is correct, and if the division by 2 isn't exact, the game rounds up, I believe. After your character's levels exceed Level 9, the game does this:
Fighter: (3 hp per level) / 2
Cleric: (2 hp per level) / 2
Again, round up.