Add rounding and currency decimal place options

[lukeholder]

Currently, the price of a product is rounded to the decimal places of the base currency, when the product is on a line item in an order/cart.

This provides consistency with summing and discount/tax calculations.

Some stores want to store products in more decimal places than the currency provides. We should look to support this, but need to consider how the order will continue to sum correctly - and have percentage-based taxes and discounts also take these options into account.

Please add your voice here with your use-cases.

[mofman]

We're in the process of building an order system for a company who supplies Home Heating Oil. The price per litre of the oil is often delimited by fractions of pence eg. £0.495. At the moment Craft will round this up to £0.50.

[mofman]

In order for us to ship this site I've had to find a work arround. What I've ended up doing is instructing the admin to multiply their prices by 10 (they only have one product - heating oil). The means rather than entering £0.495 they enter £4.95.

Then I have created an adjuster which discounts this subtotal by 90% which gives us the correct total.

Really this is less than ideal as their backend shows crazy high numbers with huge discounts.

    $adjustments = [];

    foreach ($order->getLineItems() as $item) {
        $adjustment = new OrderAdjustment;
        $adjustment->type = 'discount';
        $adjustment->name = 'Decimal fixer';
        $adjustment->description = 'Decimal fixer';
        $adjustment->sourceSnapshot = [ 'data' => 'value' ];
        
        $originalTotal = $item->price * $item->qty;
        $discountTotal  = ($originalTotal / 100) * 90;

        $adjustment->amount = -$discountTotal;
        $adjustment->setOrder($order);
        $adjustment->setLineItem($item);

        $adjustments[] = $adjustment;
    }

    return $adjustments;

[aladrach]

+1 here. Commerce 3.1 has broken my calculations for partial quantities, due to the changed rounding strategy. We have a client who wants to sell fabric by the half yard. So I wrote some logic so that they inventory by the number of half yards, and we do the conversion on the front end. However, say they want to sell it at $4.99 a yard, which is divided in half for a per half yard cost of $2.495. Commerce 3.1 now rounds that up to 5.00 per yard since it rounds before the quantity calculation