The commodity-sensitive currency had been positive earlier but ended the session down 0.07 of a cent at 102.11 cents US.
Oil prices have risen this week on fears that the conflict in Syria could widen and threaten oil shipments from the Mideast. But on Friday, the November contract on the New York Mercantile Exchange was down 21 cents to US$91.86 a barrel.
Metal prices backed off as December copper edged five cents lower to US$3.70 a pound, while December gold bullion was off $10.90 to US$1,750.70 an ounce.
The slide in commodity prices comes in the wake of a gloomy assessment of the global economy by the International Monetary Fund. On Tuesday, the IMF reduced its growth forecast for the world economy to 3.3 per cent this year from its previous estimate of 3.5 per cent.
The dollar finished this week little changed. But the currency had gained 0.21 of a cent Thursday in the wake of a better than expected reading for the Canadian trade deficit in August.
Imports and exports fell in August, narrowing the merchandise trade deficit with the world to $1.3 billion from $2.5 billion in July. Economists had expected a deficit of $1.85 billion.