They originally paid $10 each = $30
The hotel refunded $5, leaving $25 for the hotel.
They got refunded $1 each = $3
This leaves $2 for the porter. Total $5. No missing money here.
$30 originally paid -$3 refund = $27 total paid. $27 / 3 = $9.00 each paid. No missing money here either.
