As the surcharge is handled by the Tyro terminal, posBoss is unable to refund the surcharge applied to each item or the bill. The amounts are recorded but only able to be used in cash up and reporting figures.
So if you do need to refund the surcharge amount we would recommend processing the refund manually on your Tyro Terminal.
Following that, in posBoss you may want to refund the items for stock purposes, as cash. This will result in a variation between Cash/Card totals when you complete cash up. You will be up on Card and down on Cash for the day. The values should be equivalent to each other.