Ind. Code § 6-2.5-4-8

Sec. 8. An Indiana governmental entity, agency, instrumentality, or political subdivision (including a state college or university) is a retail merchant making a retail transaction when it performs private or proprietary activities that would constitute retail transactions under this article if those activities were performed by a retail merchant. However, this section does not apply to a political subdivision when it performs an activity that is related to an annual festival, carnival, fair, or similar event.