The only time that you should use a $5 Facebook ad is when you are testing a very small country in terms of population or geography. $10 conversions ads work so much better than the $5 conversions ads. However, if you are targeting a small country then $5 is enough to spread through that population.
https://dropshippinghelps.com/guide-to-5-facebook-ad-for-shopify-dropshipping/

