Costco reported higher sales and earnings than expected for its fiscal fourth quarter, proving its worth yet again as a haven from economic volatility.

The warehouse club posted earnings of $4.28 a share, while the consensus call among analysts tracked by FactSet was for $4.24. Revenue for the quarter ended May 11 was $63.2 billion, including both net sales and membership fees. Analysts had penciled in $63.1 billion.

Sales for the quarter rose 8% year over year. Same-store sales increased 5.7% -- slightly lower than the consensus estimate calling for 6% growth.

Shares of Costco were down 0.4% in after-hour trading Thursday, reversing gains immediately after the report's release. The stock is up 10% this year.

Costco doesn't provide forward guidance, given that it still reports monthly sales results.

Analysts argue Costco is less exposed to tariffs than many other retailers. About a third of the company's sales in the U.S. are imported, and less than half of those items come from China, Mexico, and Canada. The company's scale also gives it a leg up in negotiating better prices with vendors, which could help offset any existing tariff effects.

On a call with investors Thursday, executives outlined how the company is rerouting goods sourced from high-tariff countries to markets outside of the U.S., as well as working to procure more products stateside.

It also helps that Costco's shoppers are often fiercely loyal -- lured in by the retailer's treasure-hunt model and bulk pricing on everything from groceries to more discretionary purchases.

Costco stock reflects that, with shares up about 11% this year and commanding a valuation that is hovering around all-time highs. The stock trades at 56.17 times the current fiscal year's earnings, per FactSet.

Even a March earnings miss, which temporarily dragged shares lower, couldn't stop Costco's momentum for long. Although shares haven't rebounded to levels seen before those results, they have jumped 14% from the year to date low struck on March 13. That suggests the wholesale club remains a haven from tariff volatility for many investors.

That said, the company won't be entirely immune from the effects of tariffs. Costco's value-forward model means the company will try to keep prices as low as possible to maintain market share, which could come at the cost of profit margins. For instance, in the last quarter, the company decided to maintain prices on certain staple products, such as pineapples and bananas, even though import costs were higher.

"We felt it was important to really eliminate the impact there for the member by working with our suppliers and by us finding efficiencies and accepting that there may be a margin impact," said Gary Millerchip, Costco's chief financial officer, Thursday.

Not all prices will remain unchanged. Millerchip outlined how the company opted to increase prices on imported flowers, a more discretionary purchase, because team members felt "that was something that the member would be able to absorb."

The strong earnings report could keep fueling the rally, but the real test will be in the coming months as U.S. trade policy keeps evolving. If Costco is able to keep maneuvering through the tariff upheaval smoothly, it may just prove time and again why it is deserving of a premium price tag.