Hi,
Welcome to It’s FOSS Community forum.
Ah! The things you discover when you start playing with Linux.
There is one simple explanation of this: the hidden files and folders.
When you did sudo du -shc /home/*, it showed 3 directories and their sum.
And when you did sudo du -shc /home/roger/*, it probably showed a bunch of directories and files and their sum.
The difference comes from what it sees. When you do /home/roger/, you are listing the contents of the directory first and then calculating its sum. The problem comes from the display because hidden folders won’t be shown in /home/roger/ (you can see the difference by using the ls command option -a).
Since the hidden folders of your home directory was not in the output of /home/roger/*, their directory size was not counted.
The correct way to check the directory size would be to use it like this:
sudo du -shc /home/roger
This way, you are not displaying the contents of the /home/roger directory. Your system will automatically takes into account all the files and folders (even the hidden ones).
I hope I was able to solve the mystery here 
And if you want some more on du command, here is an article I wrote earlier: