Raising Money for A Non Profit via Merch Sales / Tax Implications & Best Practices

Hi, I'm working on a project where I will be selling merch online to raise money for a nonprofit.

I'm trying to figure out the best way to set this up as to avoid paying taxes on the proceeds personally and maximizing the amount of money the nonprofit receives.

I spoke to the nonprofit I'll be donating to, and they suggested that it all come in one lump sum and then it is a tax write off, but in speaking to a few business managers, that wont be a 1:1 ratio.

Does anyone have experience doing this and can advise best practices? We will be using Cargo or Shopfiy for the backend to create a custom store with multiple items.

Shipping costs will also need to be taken in to account as a separate cost against the overall profit.