Round resulting sale price to a pleasant (rounded) amount

[lukeholder]

When a sale is applied, the price of the item could result in a price that is unstrategic[0]

Sales pricing rules could have options to make the price more pleasant.

i.e

original price: $10.50
sale (%8) price: $9.66

with pricing display options on:
sale (%8) price: $9.65 (rounded to nearest .5)

[0]https://www.nickkolenda.com/psychological-pricing-strategies/

[lukeholder]

You could get around this for now with an event that modifies the sale price. The example below rounds down to nearest .50 cent increment.

use craft\commerce\events\LineItemEvent;
use craft\commerce\services\LineItems;
use craft\commerce\models\LineItem;
use yii\base\Event;

Event::on(
    LineItems::class,
    LineItems::EVENT_POPULATE_LINE_ITEM,
    function(LineItemEvent $event) {
        // @var LineItem $lineItem
        $lineItem = $event->lineItem;
        // @var bool $isNew
        $isNew = $event->isNew;

        // Modify the resulting sale price of a line item
        // round down to nearest `.50`
        $lineItem->salePrice = floor($ $lineItem->salePrice * 2) / 2;
    }
);