Gap between tiles

I've looked at a lot of tutorials and examples but I cannot seem to get my tiles to line up nicely without a gap between them.
Each image tile is exactly 100x100 pixels in size, and I have the pixels per unit set to 100. I have the camera set to orthogonal at a size of 5 (I was told this was very important). But I still can't get it to line up properly. Some of the tiles seem to fit better than others though

 

^ that image doesnt work..

 

Edited my post. Sorry