Hi Sherri,

The tilemenu doesn't have a fixed size as the images are meant to cover the tile based on the ever changing screen size. As all screen sizes are different based on what you are working on. Phone, tablet, laptop and desktop. 

The closest thing you can try is the following below in project settings, which will contain the images in each tile, but doing that the images will be fitting proportionately sometimes showing white in the background behind the image.

.tilesmenu-menu .menu-item-inner {background-size: contain !important; background-position: center top !important;}