On the April $12$ interest payment date, the outstanding balance on Home Alone Cat Sitting Service revolving loan was $$2,000.$ The floating interest rate on the loan stood at $6\mathrm{.}25\%$ on April $12,$ but rose to $6\mathrm{.}5\%$ on April $17,$ and to $7\%$ on April $29.$ If Home Alone Cat Sitting Service made a principal payment of $$1,000$ on April $30,$ what were the interest charges to its bank account on May $12?$