In the interest of everyone, I reached out to the head of the Math & Science Department and his response is immediately below.
The Texas Instruments TI – 36X Pro is required for all Math and Science courses. It is also approved to be used in a number of other courses in the other departments. Therefore should be the one purchased if the plebe wants to get only one calculator. The other calculator (TI-89), the student may find to be useful to do basic graphing etc. if they do not have their computer with them and thus is optional.