If you are using the TurboTax desktop CD/Download editions installed on your personal computer, there is a state e-file charge that is currently $25. You must have a discount to have only paid $15.
The state tax program is a free Download if you purchased the Deluxe, Premier or Home & Business desktop edition. That does not include the state e-file fee.
The state e-file charge can be avoided by printing and mailing the state tax return.
E-filing fee in desktop software
It sounds like you purchased the CD/download from a retailer that gave you a $10 discount for the state e-file fee---which would normally be $25.
Did you purchase desktop software with state software included? They sell Deluxe both with and without state software--so you have to be careful which one you choose. And even if it does have the state software download included, that is for preparing the state. There is an extra fee to e-file the state. Before March 1 that fee is $20; after March 1 it increases to $25. You can avoid the state e-file fee if you print and mail the state instead of e-filing it.