La Torre is a local supermarket chain in Guatemala. It turns out that their web page, https://latorre.com.gt lets you order on-line. Armed with that page, a reasonable location (try Guatemala City, Zona 1) and knowing that there are about 7.7 Quetzales to the US dollar you can see what groceries cost in Guatemala.
For produce, there are lots of public markets with fresher produce at better prices. For “regular stuff” the local tienda will generally have the same or better prices but if you want some Ben and Jerry’s, 
La Torre is the place to go.