Good lord - No its not a rounding error. How did you even get that ? Here is the cost of illegal immigration to taxpayers:
https://budget.house.gov/download/the-cost-of-illegal-immigr...
It is ~42 billion for welfame, $70 billion USD for schooling, $7.5 billion for the uninsured, etc, totaling to around ~150 billion. This is also around the figure confirmed by DOGE.
It would be nice if you can refute the data on facts.