Deposits must exceed $1.02 in order for them to be credited to your virtual USD account.
Note however that incoming transactions under this amount will still appear in your transaction history, as payment platforms like PayPal e.g. often make these micro-deposits as part of the verification process, before allowing you to send larger amounts.
Deposits below the required transaction minimum will not be credited or returned however. This is standard practice, as the cost of returning such small amounts often exceeds their value. We instead accumulate these micro-deposits and onramp the combined amount into your virtual USD account once it exceeds the minimum. Until that point, those transactions will show up as 'pending'.