It depends on the regulations where you are and the tax situation you are in. In the UK the first £12k gains are free.

The US is kind of complicated with different rates for short term and long term gains.

I declared UK crypto gains recently. It can get complicated if you try to follow all the instructions properly.

It would likely count as a sale and incur a capital gains tax. You'd spend $5 for that pizza and then another $2.50 on capital gains tax. Probably some more on eating the bid-ask spread.