Another way to think about it: for every 100 units in 10, you take 68. That adds up to 6.8.
On a 68% off sale, an item originally priced at $10 would be discounted by $6.8, bringing the price to $3.2.
Whether you are calculating a discount, a tax, a tip, or a commission, the math is always the same: multiply 10 by 0.68.