Is it a $5 or a $10? Neither is a great rarity, but Merchants Bank values seem to be trending upward generally.
Catalogue values:
$5 $10
Good 225. 250.
VG 450. 500.
Fine 675. 750.
I would suggest not going over book for a very low grade note and definitely not for one with problems (such as erasure marks, washed, pressed senseless or trimmed edges) but you could, I think, safely go full cat. or a little over for a nice, well centred fine. Both the $5 and $10 are attractive notes.