Is paying a sum of money to someone to help me enter a tender (for renting a building for parking), with an agreement to return the money if the procedures are not completed, considered a bribe?

If the person's task is to offer a bribe, then it is not permissible. However, if their role is only to prepare specifications and costs and submit them for a tender, then it is permissible, and they are entitled to the mentioned amount if the merchant's transaction is accepted.