Frankly, if you are dealing with a rule-bound, rigid teacher, I'd break out the IEP card right away. The teacher is unlikely to be flexible and bend the rules for your child, so make the accommodations part of the rules. And request a different teacher if this one shows any signs of resentment or bullying over the need for accommodations.
If your child qualifies for an IEP, and math fluency is a problem that is preventing access to the curriculum or impacting his ability to derive educational benefit from the instruction, and intensive tutoring would help with fluency, the school should provide special education services including tutoring in the IEP, as well as requiring accommodations in the classroom.
