No, pennies will not have any benefit; when copper is used to combat plant diseases it's in spray form, to treat foliage and sometimes dormant twigs. It suppresses the stage of infection where spores enter leaf tissue, especially when foliage stays wet for long periods since this makes it easier for fungal and bacterial pathogens to enter the leaf. Copper buildup in soil can be toxic to roots after a certain level, so any copper-based fungicide product will probably include a limit on applications per year in the label instructions to reduce this risk.

Early Blight is one of the most common tomato diseases in our area, though they can contract several infections and symptoms might overlap a bit. Management tips are included on the linked page for Early Blight.

Miri