public void purchase(String name, double price, SaleItemType type, boolean isImported) {
        switch (type) {
            case Food:
            case Book:
            case MedicalProduct:
                saleItems.add(new SaleItem.SaleItemBuilder(name, price)
                        .isImported(isImported)
                        .isSalesTaxExempt(true).build());
                break;
            case MusicCD:
            case Perfume:
                saleItems.add(new SaleItem.SaleItemBuilder(name, price)
                        .isImported(isImported).build());
                break;
        }
    }