public function calculate(): void 	{ 		foreach ($this->products as $product) { 			$this->quantity += $product->getQuantity(); 			$this->totals->setTotalPrice(MathMoneyOperations::calculate($this->totals->getTotalPrice(), $product->getTotalPrice(), '+')); 			$this->totals->setTotalDiscounts(MathMoneyOperations::calculate($this->totals->getTotalDiscounts(), $product->getTotalDiscounts(), '+')); 			$this->totals->setTotalTax(MathMoneyOperations::calculate($this->totals->getTotalTax(), $product->getTotalTax(), '+')); 			$this->totals->setTotalPriceWithDiscounts(MathMoneyOperations::calculate($this->totals->getTotalPriceWithDiscounts(), $product->getTotalPriceWithDiscounts(), '+')); 		} 	}