NEW YORK (CNNMoney.com) -- Home mortgage rates ticked lower after Federal Reserve Chairman Ben Bernanke said the central bank will continue to keep interest rates low.

The average 30-year fixed mortgage slipped to 5.55% from 5.58% the week prior, and the 15-year fixed fell to 4.89% from 4.93%, according to the weekly national survey from Bankrate.com.

Recently rates have been "yo-yoing as corporate earnings announcements and economic data toy with investor sentiment," the report noted.

On Wednesday Bernanke gave his semi-annual congressional testimony on the state of the economy, saying the central bank will "likely keep interest rates low for an extended period of time," the Bankrate report noted.

A separate Thursday report showed sales of existing homes disappointed again in June, rising just 3.6%.

Current mortgage rates remain much lower than last year's levels, when the average 30-year fixed was 6.77%, according to Bankrate.com.

At the current rate of 5.55%, the monthly payment on a $200,000 mortgage would be $1,141.86, or about $158 less than the monthly payment at last year's rate.

Adjustable-rate mortgages: ARMs "continue to post mixed results," the report said, with the average 1-year ARM rising to 5.23% from 5.22%, and the 5-year ARM falling to 4.93% from 4.98%.