When it is asking for how much of my Box 12 retirement contributions went to a SIMPLE Roth IRA plan, is it asking for the pre or post tax contributions?

Sort of, but it's asking about the type of account to which the contributions were made.  Contributions to a traditional SIMPLE IRA can only be pre-tax contributions while contributions to a SIMPLE Roth IRA can only be after-tax contributions.  Because both are reported the same way on your W-2 as if they were pre-tax, TurboTax needs to know if the contribution was actually to a SIMPLE Roth IRA so that it can be added back to your taxable income.

If you don't know if your SIMPLE account is traditional or Roth, check your year-end statement or ask the IRA custodian.