Energy to change copper from room temp solid into liquid is the specific heat of 0.385 Joules/gram * about 1100C + the heat of fusion of 210 Joules/gram, so, about 630 J/g which is 0.170 watt-hours per gram.

A melt of 1,000,000 pennies would be about 3000kg, so 510 kWhr of energy, and using an electric furnace that is about 50% efficient at putting its heat into the melt, that is about 1000 kWhr at the wall outlet. I've been in foundries with crucibles that could do probably about 200kg copper pours, with a furnace power of about 100kW, you'd do a full crucible melt every few hours, and you'd run this continuously until you're out.

If you live somewhere with electricity, say, $0.15/kWhr energy, that is a melt cost of $150.

1,000,000 pennies at 3 cents per worth of copper would be about $30,000 in copper reclaimed over the course of a few days.

So, it would be absolutely profitable in large quantities, assuming you ... already work in a foundry.