Okay- First are you doing Calculated Shipping measurements in metric? Remember Canada Post went metric in 1974 and any other measures are at best, approximations.
Second, if the buyer pays more than your shipping (and handling , bubblewrap ain’t free) costs, then with no fanfare but a polite email, you send a small refund, who do you think is going to complain?
Handling is a legitimate cost. If you don’t want to put it into your S&H, then allow for it in your asking price. Shipping is not meant to be a profit centre, this was one reason for the recent addition of S&H FVFs, but it is not meant to be a loss leader either. We are here to make money.
Third, if you refund, the eBay/PP fee should be part of the calculation (along with the cost of bubblewrap). If the postage is $2 more than your S&H fee, the refund would not be $2, in other words, it would be $1.50 or so. (And don’t forget the tax and fuel surcharges on your postage.)
Can you use standardized packaging? There are boxes available that will fold into several sizes and if you use those you will know how big your package will be. And you can weigh them along with the bubblewrap.
And if you are using Paypal labels , you have two further advantages. The labels do not note the postage paid and you don’t have to go to the PO with your parcels. You can just drop them into the nearest corner postbox (but not the one outside the high school).
Nothing can be done about exchange rates. All exporters (Canadian, American, overseas) work with them. At best you can make sure that you are listing all your prices in US dollars and hope for the best.
