How to represent tally/five-bar-gate in unicode?
A proposal to include “Western-style tally marks” (L2/16-065, PDF) was accepted by the Unicode Technical Committee in May 2016.
This introduces two characters:
u1D377- TALLY MARK ONE - ð·u1D378- TALLY MARK FIVE - ð¸
As of early 2018, these characters are “accepted by UTC and in active ISO technical ballot (or on hold for ballot)”. Their adoption progress can be monitored in the proposed characters pipeline.
You could use 卌 U+534C (in fact, it's a Chinese symbol for 40)