That is a good question.
IMSC, at a school I worked, the HC's stipend would increase "X" amount for each level of the tournament they won.
Example purposes only----base stipend was 10k
add in $1,500 for a sectional championship, $2,000 ($500 added onto the already earned $1,500 for the sectional championship and so on for each additional level won) for a regional championship, $3,000 for a SS championship, and $5,000 for a state title.
This was many, many years ago, so I am not sure how that school pays now.