How to upload a custom amount to the steam wallet?

[Banana Soufflé]

Problem
I have some residual cash on my paysafecard. Using it up to reduce the amount to exactly 0 is almost impossible. So unless I buy a new paysafecard code, which I don't want to, I will lose that residual cash.

Idea
I would like to upload the residual cash into my steam wallet. I am buying regularly games and even better, steam wallet allows for mixed payment on a purchase i.e. a portional credit cared and a portion with steam wallet.

Question
Is there a way to upload a custom amount into the steam wallet, thus I could reduce the paysafecard saldo to exactly 0?

(If not I would like to know if there is a way in steam to mix for a purchase a paysafecard code payment with a credit card payment)

[cSg|mc-Hotsauce]

For custom amounts over the minimum allowed to purchase, use this guide...

https://steamcommunity.com/sharedfiles/filedetails/?id=328859255

Any amount below the minimum you are allowed to add will not work.

[Banana Soufflé]

Thx for the guide. However in my case it is about a residual cash amount i.e. below 5. But your post answers my question. It doesn't seem to be possible.