Look here, everyone can see each round...
As early as the 5th round $20,000. By the 7th round 2 playerrs si9gned for $5,000 and 3 others for $20,000. By the ninth round several signed for between $1,000 to $10,000. Then in round 11 some early round prospects started to go. In the 11th round everyone got between $100,000 and $1.2 million. This is due to the slotting rules.
https://www.perfectgame.org/Dr...Signings.aspx?y=2016
You can also check past years along with each round above.