Space Statistics adds the total attachment size incorrectly

On the Space Statistics built-in script (admin and space admin), the attachment size is rounded to the nearest megabyte. This is fine, but the total size should add the actual attachment size, then round it to the nearest megabyte, not add the rounded number.

For instance, if there is one attachment at 4.4mb the rounded size would be 4. But if there are 10 attachments each at 4.4mb, it should be adding the actual size of each (4.4x10=44) not the rounded size of each (4x10=40).