The warehouse chain spent about $281 million on employee bonuses and sanitizing its warehouses in the fourth quarter, mirroring a trend of rising costs across U.S. retailers during the health crisis.

Costco had estimated in May that COVID-19-realted costs would exceed $100 million, but would be lower than the $283 million incurred in the prior quarter.

"$281 million is over $100 million but quite a bit larger," Chief Financial Officer Richard Galanti said on an earnings call.

The company cited the $2-an-hour premium paid to employees as a factor for the jump in costs. The bonus costs Costco $14 million a week.

"We've committed to doing that at least through, I believe, the first eight weeks of this fiscal quarter," Galanti said.

Several U.S. retailers, including Kroger Co and Amazon.com Inc, have come under fire for stopping hazard pay for their workers.

Higher demand for fresh produce, appliances and gardening and sporting goods helped Costco's total revenue climb 12.4% to $53.38 billion in the quarter ended Aug. 30, beating the average estimate of $52.08 billion, according to Refinitiv data.

Traffic at the warehouse chain, where customers typically buy items in bulk at lower prices, also ticked up in the quarter, after declining about 20% in April, as COVID-19 restrictions eased and it brought back food samples.

Revenue from memberships rose 5.3% to $1.11 billion, while online sales nearly doubled.

Excluding items, Costco earned $3.04 per share, beating estimates of $2.84.

(Reporting by Praveen Paramasivam in Bengaluru; Editing by Aditya Soni)