preposition + amount of

[Roadster]

I am not sure about the preposition in a sentence like this:
We are referring to your invoice to/in the amount of $5,000.

 

[Matthew Wai]

'Your invoice for $5,000', according to the Oxford dictionary.

Not a teacher.

 

[emsr2d2]

If you must use "amount" then use "in the amount of".