The last time interest rates were slated to go up for subsidized Stafford loans was only a year ago, though as it came during the peak of the US presidential campaign, Congress managed to avoid the increase.This time around, it looks as though congressional gridlock will end up costing college students $5,000 extra on repayments for new school loans, RT reported.The rate for the Stafford loans, a cornerstone of financial aid packages around the country, is set to increase from 3.4 per cent to 6.8 on July 1, right on time for the fall semester. Currently, US student loan debt tops $1 trillion.