> ## Documentation Index
> Fetch the complete documentation index at: https://docs.centsless.org/llms.txt
> Use this file to discover all available pages before exploring further.

# Centsless API: Jurisdiction-Aware Cash Rounding

> Centsless provides real-time cash rounding compliance for all enacted U.S. states. POS vendors integrate once to cover every merchant on their platform.

Centsless is the compliance infrastructure layer for cash rounding in the post-penny economy. Penny production ceased in November 2025, and eight U.S. states have enacted cash rounding legislation - each with a different methodology and enforcement model, and no federal standard to unify them. Centsless solves this for POS vendors: integrate once through the API, and every merchant on your platform gets automatic multi-state compliance coverage with a cryptographic audit trail on every transaction.

## What the API does

<CardGroup cols={2}>
  <Card title="Jurisdiction Resolution" icon="map-pin">
    Send a ZIP code or state. Get back the correct rounding rule, enforcement level, and legislation reference. Covers 33,000+ U.S. ZIP codes.
  </Card>

  <Card title="Transaction Processing" icon="cash-register">
    Submit a cash transaction. Receive the legally correct rounded amount, compliance certification, and fraud score in real time.
  </Card>

  <Card title="Audit Trail" icon="shield-check">
    Every transaction is hashed into an immutable chain. Overrides, voids, and refunds are tracked with employee attribution.
  </Card>

  <Card title="Compliance Export" icon="file-csv">
    Export a 53-field CSV with the complete transaction lifecycle for regulatory reporting and audit evidence.
  </Card>
</CardGroup>

## Enacted states

The following states have enacted cash rounding legislation as of April 2026. All eight require sales tax to be calculated on the pre-rounded amount.

| State      | Bill     | Method                     | Enforcement | Scope                 |
| ---------- | -------- | -------------------------- | ----------- | --------------------- |
| Arizona    | HB 2938  | Swedish rounding           | Mandatory   | All retail cash       |
| Indiana    | SB 243   | Three-tier operator choice | Permissive  | All cash + govt taxes |
| Tennessee  | HB 1744  | Symmetrical (safe harbor)  | Voluntary   | Retail cash           |
| Washington | SHB 2334 | Symmetrical                | Permissive  | In-person cash        |
| New Mexico | HB 291   | Delegated to Dept          | Narrow      | Tax/MVD fees only     |
| Utah       | HB 597   | Not prescribed             | Narrow      | Alcohol sales only    |
| Idaho      | S 1350   | Swedish rounding           | Permissive  | All retail cash       |
| Oregon     | HB 4178  | Symmetrical                | Permissive  | All retail cash       |

## Integration paths

The API supports three ways to resolve the correct jurisdiction for a transaction:

1. **ZIP code** — Send `zip_code` and the engine resolves state, county, city, and rounding rule automatically. This is the recommended path for most integrations.
2. **State/county/city** — Send location components directly for explicit resolution without ZIP lookup.
3. **Explicit override** — Send `cash_rounding_mode` to force a specific rounding method. Useful for testing and development.

## Key rules

Before you integrate, make sure your implementation accounts for these rules:

* Cash transactions are rounded per the jurisdiction rule
* Card transactions are never rounded
* EBT/SNAP transactions are never rounded, regardless of jurisdiction (7 CFR 278.2)
* Sales tax is always calculated on the pre-rounded amount
* Every transaction receives a compliance check and fraud score
* Every transaction is added to the immutable audit hash chain

## Getting started

<CardGroup cols={2}>
  <Card title="Authentication" icon="key" href="/authentication">
    Learn how API keys work and how to authenticate requests.
  </Card>

  <Card title="Quickstart" icon="rocket" href="/quickstart">
    Process your first transaction in under 5 minutes.
  </Card>
</CardGroup>