How do you keep track for tax ?

It seems like a lot of people DCA on here and was wondering how you keep track for tax.

Some exchanges keep track of buys for you which helps. But does that include fees or no. When you sell, then do you need to know your average price.

In short term this is not bad but long term can add up with many different coins. Especially if you plan on holding for years.

So if anyone has a good way to do it would help a lot of us out.

And if there is a good way to track it for past buys/ swaps.

Thanks