var amount = 100,
    coin = [1, 5, 10, 25]
var t = [1];
for (t[amount] = 0, a = 1; a < amount; a++) t[a] = 0 // initialise t[0..amount]=[1,0,...,0]
for (var i = 0, e = coin.length; i < e; i++)
    for (var ci = coin[i], a = ci; a <= amount; a++)
        t[a] += t[a - ci]
document.write(t[amount])