The issue of extra charges is prevalent not only with overseas credit card transactions but can also arise with transactions on local websites with an “.sg” suffix, where payments are processed overseas (“Riding with Uber? Read fine print on extra charges“). Even though you are billed in Singapore Dollars (SGD), some banks and credit card companies will charge you about 1% of the total fee (depending on which credit card you used). According to this source, a few financial institutions such as ANZ, UOB, HSBC, CIMB, Maybank, Standard Chartered, POSB, DBS, Bank of China may charge an additional (Dynamic currency conversion) fee, alternative option is to link these cards to Paypal to avoid further transaction fee.
Uber is not the only company that have their payment processed overseas, others that Askmelah is aware of are Cheaptickets.sg and Groupon, in the case of Cheaptickets.sg the extra fee will be much higher as hotels and airticket costs are many folds that of Uber!