You can tag groceries with a store name (click the grocery to open up the grocery details and select the store). This will place a tag with the store name on the item to the right hand side of the grocery list.
If you want to only show items on the list you can tap one of the store tags on your list. This will filter the list to only show items tagged for this store as well as all items that do not have any store tag (that can be bought at any store).
To remove the filtering, just tap the store tag on the list again.
