The transaction fee is too high for a $20 transaction. Leave it in your wallet until you accumulate more BTC from your customer will be a better way out.
It's sure worth it if you want to buy something up to 16$ and wouldn't want to go out of your way to and expose your privacy because these micro transactions come in handy when you want to protect your privacy and at that point it will be worth every one of your bitcoins. I gamble every weekend and i wouldn't gamble without my bitcoins or leave my bitcoins for fiat.