Since so many mods/modpacks attended to create some new currencies, adding a tag for tax may be beneficial to the compatibility with others.

Yes, thank you for your response.

I planned to implement this as a config because I need a value for each item. A emerald for example is more worth than a copper coin. Does this work for you?

Can you make it so this support multiple items, along with the chance of how rare the item will be offered by the villager?

Yes, that's why I said a config might be more suitable :)

Added