<pendantic>
If you actually mean 5 MiB (that is, 5x1,024^2 or 5,242,880 bytes, and not 5x1,000^2, which is 5 MB), then that equals 5,120 KiB (or 5,242.88 KB or 5.24 MB.)
If you really did mean 5 MB (5,000,000 bytes), then that would indeed be 5,000 KB (or 4882.81 KiB or 4.77 MiB.)
Or if you...