Fees

Free transactions: value => 0.01 (10₥), smaller than 1000 bytes, having a priority high enough

Where transactions do not meet these criteria then

• Default minimum fee: 0.0001 (0.1₥) per 1000 bytes
• Network minimum fee: 0.00001 (0.01₥) per 1000 bytes

The minimum transaction fee can be overridden with the mintxfee configuration variable.

Transactions with higher priority and higher fees are given preference. For more details see Transaction Fees on the Bitcoin Wiki.

The dust limit is 0.00000545 (0.00545₥), any amount lower than this is considered spam.

Best Practice (October 2014)

Try to keep on chain transactions above 0.01 (10₥), and apply a fee greater than 0.00005 (0.05₥) per 1000 bytes.