If you have US$ cash in your PayPal account, you can:
1) convert from one currency into another and keep it in your PayPal account to fund your future purchases. You could maintain both US$ and Cdn$ balances
2) convert from US$ into Cdn$ and withdraw to your Canadian bank account (no charge if you withdraw more than $150)
3) leave the cash as is until you need it.
4) alternatively, if you have a large volume of business, you can open a bank account at a bank located in the USA and transfer those US$ to that bank without conversion (a US dollar denominated account held at a Canadian bank cannot be used for that purpose). However, you will need at some point to bring back those US$ into Canada and will have to convert at that time. The US based account is not worth it unless your monthly volume is substantial (US$10,000+)
