My DnD 5e players have stopped keeping track of ammunition, rations, torches, etc, because it's something they use all the time and their character sheet starts looking rubbish or being torn from erasing/re-writing the numbers all the time.
What we eventually set out to do is to spend an amount of gold per city visit that matches buying enough food/supplies for a week of adventuring. In specific situations where I know these will be a problem, I specifically ask players to keep tabs on the items.
Is there a nice way to keep track of items whose quantity changes constantly? Someone suggested to me to use decks of cards, e.g., each player has a deck of ammo, a deck of rations, etc. As they are used, he gives me back the card. On towns, he buys these cards.
Preferably, something low-cost (or free), not on electronic devices (let's not make excuses to have phones at the table), easy to use and that doesn't require much maintenance.