Toilet tissue sold for household use is exempt from New Jersey's 7 percent sales tax.
But the couple, Jacqueline Taufield and Robert Arnold, said that they were charged the tax when they purchased Charmin toilet tissue on July 26, 2015, from a Costco in Wayne, New Jersey, and then again when they picked up some more Charmin in a Costco in Hackensack five days later.
The suit said that when the Leonia couple complained to Costco management after realizing they had been charged sale tax improperly, "they refused to issue a rebate to them."
The couple's lawyer, Rosemarie Arnold, said, "Rather than refund [Robert's] money, they told him, 'Well, if you believe that, you have to mail your receipt to the corporate headquarters along with a letter and tell the corporate headquarters how you were improperly charged tax.'"
The couple was "annoyed and angry" about the charge, and that response, said Arnold, who is not related to Robert.
"The obvious solution is to say, 'You're absolutely right ... we made a mistake, here's your money back,' " the lawyer said.
The suit says that Costco "despite being aware of the illegality of their actions... continues to cheat their customers, causing them to incur monetary damages when they purchase toilet tissue."
The claim, filed in Bergen County Superior Court, alleges violation of the New Jersey Consumer Fraud Act, breach of contract, unjust enrichment, negligence, violation of the state's "Truth-in-Consumer Contract," and fraud.
A Costco spokeswoman, when asked for comment on the suit, said, "Unfortunately, we are not able to provide a response at this time."