calculateTotals

calculateTotals refers to a function, method, or workflow used to compute aggregate monetary totals across a collection of line items. It typically derives a subtotal from item prices and quantities, then applies discounts and taxes to yield a grand total. In many contexts, it can also produce per-category or per-customer totals.

Inputs usually include a list of items with fields such as price, quantity, taxRate, and discount, along with currency information. Some implementations accept precomputed line totals or a data structure with a total field. Optional parameters may specify tax rules, rounding mode, and whether taxes are calculated before or after discounts.

Algorithm: often a single pass over items to compute lineSubTotal = price * quantity, apply discount to reduce the subtotal, sum all line subtotals, compute tax on taxable amount, and combine to determine grandTotal. Some variants perform grouping (e.g., by customer or category) or incremental updates as items change. Rounding is typically applied at the end or per line depending on currency rules.

Outputs include an object with fields such as subtotal, discountTotal, taxTotal, grandTotal, and currency. Some implementations return per-line totals, or a breakdown by tax rate or category.

Considerations: correct handling of currency precision and rounding errors, null or missing values, negative amounts from refunds, tax jurisdictions, and performance for large item sets. Tests should cover edge cases like zero quantities and free items.

Related concepts: invoicing systems, shopping cart total calculation, financial reporting, and spreadsheet functions that aggregate sums with taxes and discounts. In codebases, calculateTotals is often part of a utilities module or an accounting/computation service.