The head of the math department at our school was recently told something similar to what Hayley is talking about regarding our state math assessment.
If a student scored in a certain percentile on the reading assessment last year, they can have the math test read to them on the computer regardless if they have an IEP or 504.
Most of our school qualifies for this.
To answer OP's question, not at my current school, 30 percent of our population has an IEP and we are stretched too thin to even consider this.
At my previous district some regular-ed teachers would try this (send non-IEP kids to another room for tests) and would often get away with it, depending on the administrator.
This was usually with high-maintenance parents who did want their child to have an IEP, but wanted all the special ed help.