Hi there accounting437,
Setting up and running different reports is the perfect way to gain a better understanding of your business' current and future finances. QuickBooks Desktop simplifies the process of tracking your cash flow, so I'm glad you've been taking advantage of these features. Let me go over why you're seeing that $0.01 discrepancy between your UK Accounts Receivable and your Balance Sheet Report.
You're assumption that the discrepancy you're seeing is as a result of rounding, is correct. QuickBooks Desktop only rounds to the third decimal point. Sometimes this causes small changes or discrepancies in your books such as the one you've noticed. If the discrepancy you noticed was larger, it'd be a good idea to review your transactions and take currency into consideration, but in this case at an only $0.01 difference, there isn't anything to worry about.
Thanks for being a member of the QuickBooks Community. Have a great day!