Token size and grid

Occasionally I like to make a token slightly larger or smaller such that it does not fit perfectly into the grid. As a token is moved around, it always snaps to grid in the top left corner. Is there a way to instead make tokens always centered on a grid square?

Not automatically. You can just hold down the ALT or OPTION key on your keyboard, this will let you set the Token off-grid (non-snapping). 

I am hoping this will be an option in Jumpgate. It would also allow for slightly oversized tokens. In the meantime if you have general skill with an image editor, you can resize a token to make it smaller than the file dimensions (more transparent space around it). The image will snap to the corners, but the smaller token will be centered in the area. This is how Roll20 handles Tiny tokens in their modules. Here is an example.

Thank you.