If someone paid partial cash for my vehicle, and I financed the rest, how do I report the sales tax?

You can deduct the total sales tax shown on this invoice.

I think @MinhT1 is understanding your post in a different way than I do. Your statement "I financed the rest" indicates to me a seller financed loan. If this is the situation then please clarify so that @MinhT1 can clarify their response if deemed necessary.

Thank you @Carl . @MinhT1 to clarify, I did the financing through a bank (the one that the authorized dealership offers financing through). Just to be sure- does this change your answer @MinhT1 

No, financing through a dealership does not change the answer.  When you pay sales tax and take on a loan/liability for it, it is considered like you paid for the entire thing even though you are making payments.