In Shopwave you can edit a product's price for the current sale by changing the price of a product in the basket. You can also apply a promotion to all eligible products in the basket, see 'Apply Promotional Basket Discounts'.

Tap on the product in the basket:

Tap on the price field:

The price can be increased or decreased by an 'Amount' or 'Percentage'. 'Amount' is selected by default. Type in an amount:

When you type in an amount, the original price and new increased price is displayed. If you would like to reduce the price by the same amount, select the '+/-' button on the number pad:

Tap done to apply the new price to to the product in the basket:

MODIFY PRICE BY PERCENTAGE

In price edit, tap 'Percentage' to edit the price by the percentage you enter: