The ROAS where your ads stop losing money, from your price and costs.
Profit per order = price − product cost − shipping − feesMargin before ads = profit per order ÷ priceBreak-even ROAS = 1 ÷ margin before adsBreak-even CPA = profit per orderThe ROAS where ad spend takes all the profit from a sale. Above it you make money; below it every sale costs you.
Same point, other unit. Break-even CPA is the most you can pay for one order: your profit per order before ads.
Then no ROAS breaks even: each sale loses money before you spend on ads. Change the price or the costs first.
Without. Use what you keep from a sale: after VAT or sales tax, and after discounts.