Monzo £5 Round Up

// grab the value of the purchase (eg. 4.3)
var costRaw = Monzo.cardPurchase.AmountInAccountCurrency;

// convert it to a number value
var cost = parseFloat(costRaw);

// round it up to the nearest full integer (eg. 5)
var costRounded = Math.ceil(cost / 5) * 5;

// work out the difference in the rounding up (eg. 5 - 4.3 = 0.7)
var costDiff = costRounded - cost;

// some form of round up accelorator
var costDiffMult = costDiff * 1;

// convert to string
var totalRoundup = costDiffMult.toFixed(2);

// set the rounded up value to be moved to the pot
Monzo.potDeposit.setAmount(totalRoundup)