Check if receipts are thermal. Run your fingernail firmly across the paper and if its thermal it will leave a mark. Make sure you check both the front and back side of the receipt.
Thermal receipts cannot be recycled. The ink used on the ‘thermal’ type paper contains BPA (now banned in specific types of plastic) and is tricky to remove during the recycling process. Due to the type of ink used that contains BPA it is easily transferrable and contaminates what it comes into contact with.
Unfortunately thermal receipts need to go into general waste, or you can refuse receipts and ask the business to email them if you need to keep them for record purposed.