Change Damage Calculation for Rounded HP Values

**Describe the bug** The game currently uses exact HP values for damage calculation. It should perform a damage calculation on rounded HP values. This means that when a unit is attacked or attacked by, instead of using 57hp as the value for calculation, it would use 60hp (for example). The specific rounding method to be used (e.g., always rounding up) should be discussed in this issue. **To Reproduce** Steps to reproduce the behavior: 1. Start a match and attack a damaged unit **Expected behavior** The game should perform a damage calculation on rounded HP values. **Desktop (please complete the following information):** - Game version v0.7.4