The greenback firmed on Tuesday as share prices fell, prompting  investors to shed perceived riskier currencies. Despite better than  expected numbers from the Institute for Supply Management, shares on  Wall Street showed only muted enthusiasm to the data and quickly lost  ground, lifting the U.S dollar, which has tended to be used as a safe  haven against losses in equities. Ahead of the U.S. jobs data later  today, traders said players were anxious about any negative surprises.  As the market has become less sensitive to positive surprises from the  U.S economic data, the effect of any weak figures would be bigger than  the effect of any positive numbers.