How can i lock an object to grid in my game ?

Recently I was working on a script for placing down objects by clicking in positions and I had to figure this out myself, I'm not sure if you're in UnityScript or C# but I usually work with C# so I'll work with that, if you happen to be working with UnityScript it's not too difficult to convert.

What I decided to use after a bit of research was Mathf.round, this converts a float into an int and if it's given a decimal .50 it will convert into the closest even number, never an odd. Here's how I did it and how you'll probably do it too.

 Vector3 x;
     
     void Start () {
         x = Vector3 (1.51, 7.34, 1.564);
         x.x = Mathf.Round (x.x);
         x.y = Mathf.Round (x.y);
         x.z = Mathf.Round (x.z);
         print (x);
     }

This code will output (2, 7, 2).

You can also round to the nearest .50 with this method.

 Vector3 x;
         
         void Start () {
             x = Vector3 (1.51, 7.34, 1.564);
             x.x = Mathf.Round (x.x * 2) / 2;
             x.y = Mathf.Round (x.y * 2) / 2;
             x.z = Mathf.Round (x.z * 2) / 2;
             print (x);
         }

This code will output (1.5, 7.5, 1.5).

You could also round to the nearest .25 by replacing the 2 and / 2 with 4 and / 4.

Hope this helped.