Keying in a transaction is more expensive than swiping a card due to the assessment of card-not-present fees. If you have the Go Plan, the keyed rate is 3.70% + 5 cents per transaction for all card types. If you have the Pro Plan, the keyed rate is 2.80% + 5 cents per transaction for all card types.
If you need to run a transaction but do not have the device handy, you can key in the transaction using the Spark Pay app. You can also key the card data in if a transaction is declined when you swipe the card.