There's a few things that you can try, depending on what keys you're more
comfortable with using.
After entering a value in B5, if you start with and then continue to use the
<Tab> key to register the entries, when you come to the last cell, use
<Enter>.
That will move the focus to the cell *under* the first cell that you used
the <Tab> on.
You could select your entire range of data entry, and continue to use the
<Tab> key, and the focus will remain within the selection, following a
left-to-right direction..
If you prefer to use <Enter>, before selecting the range, go to:
<Tools> <Options> <Edit> tab,
And change the "MoveSelectionAfterEnter" option to "Right".
This makes <Enter> mimic the <Tab> key.
Or, to use <Tab> and/or <Enter> and still have the focus follow a set path,
check out this old post for a procedure that's more conducive to
non-contiguous cell selection, but still might be of interest to you:
http://tinyurl.com/39vzv