[semafour]

Credit card rates with your own merchant account are 3% - 8%, depending on your industry and chargeback history.

Federal Marginal tax rates are 10% - 38%, plus maybe 5% in MN.

If they are giving you a 5% - 10% discount for cash, sure, it's probably because they appreciate skipping the credit card. If they give you a larger discount for paying in cash, they probably aren't reporting the income.

[EADGBE]

CC rates can be negotiated down below 3%.

[semafour]

For card-present goods and services it's likely lower, but for card-not-present online software sales from a small company, rates with your own merchant account can be even higher than 8%. This is a big advantage of using Stripe and the like.

[supergeek133]

Depends on the business.

[supergeek133]

Yes that's for sure, I'm just stating all the causes of the proliferation of this problem.