BALTIMORE — A Maryland woman recently noticed something unusual during several visits to her local McDonald’s. She told WMAR-2 News Mallory Sofastaii she wasn't receiving exact change.

When she asked about it, the cashier told her the restaurant was rounding cash transactions because pennies are no longer being produced.

The explanation sounded unusual, but under a new Maryland law, it may be perfectly legal.

In May, Maryland enacted a law allowing businesses to round cash transactions to the nearest nickel when exact penny change is unavailable.

The law was designed to address the growing shortage of pennies and provide businesses with a uniform way to handle cash transactions when one-cent coins are not readily available.

The practice, known as cash rounding, is already used in several countries and has been adopted by some retailers in the United States.

The rounding applies only to the total price of a cash purchase.

If the total ends in:
1 or 2 cents: Round down
3 or 4 cents: Round up
5 cents: No change
6 or 7 cents: Round down
8 or 9 cents: Round up

That means a purchase ending in $10.02 would become $10.00, while a purchase ending in $10.03 would become $10.05. Sales tax is calculated on the original price.

For some shoppers, seeing a total adjusted by a penny or two can be surprising.

Consumer complaints about cash rounding surfaced even before Maryland's law officially took effect, with some customers questioning signs posted at local businesses explaining that cash purchases would be rounded to the nearest nickel.

RELATED: Out of pennies: Maryland shoppers see cash totals rounded at checkout

"I was surprised when I walked in one day and saw the sign posted about rounding my purchase up to the nearest nickel without even asking me. Do I want to donate it to charity? Do I want to do something else? What if I already have my exact change?" said Phyllis Atkins-Mackey when she spoke to Sofastaii in January.

The law applies only to cash transactions.

Customers paying with a credit card, debit card, Apple Pay, or another electronic payment method must still pay the exact amount owed.

According to CommonCentsAct.com, 18 states have enacted cash rounding laws. And the federal legislation, called the "Common Cents Act," is still making its way through Congress.