3rd version

import net.minecraft.item.ItemStack;
import net.minecraft.item.Item;

public class Coin extends Item {
    private final int[] metadata = new int[]{ 1, 2, 5, 10, 25, 50, 100};
    private final ItemStack[] coinValues;

    public Coin() {
        super(1234);

        coinValues = new ItemStack[metadata.length];
        for (int i = 0; i < metadata.length; i++) {
            coinValues[i] = new ItemStack(this, 1, metadata[i]);
        }
    }

    public void registerRecipes() {
        for (int x : metadata) {
            registerRecipes(x, 0, new ItemStack[9]);
        }
    }

    private void registerRecipes(int left, int index, ItemStack[] recipe) {
        if (left > 0) {
            if (index == 9) return;
            int limit = index == 0 ? left : Math.min(left, recipe[index - 1].getItemDamage());
            for (int x = 0; x < metadata.length; x++) {
                int v = metadata[x];
                if (v > limit) break;
                recipe[index] = coinValues[x];
                registerRecipes(left - v, index + 1, recipe);
            }
        } else {
            // new CoinRecipe(Arrays.copyOf(stacks, index));
        }
    }
}