If you are getting a Magento error “PayPal gateway has rejected request. The totals of the cart item amounts do not match order amounts (#10413: Transaction refused because of an invalid argument. See additional error messages for details).” You need to do the below.
To clear this error on your Magento shopping cart
Login to you PayPal account
Navigate to your Profile name on top left corner
Click on Account settings
On the net page, click Payment preference
On Payment preferences, on Block payments > Click Update
On the next page under Block accidental payments: > Select No, allow multiple payments per invoice ID
You can now click back on top right corner and logout.
Test Magento shopping cart if PayPal works as normal.