# pos_payment_method_cashdro_rounding

Sends the CashDro the amount the customer is really expected to pay — the due
amount with the PoS **cash rounding** applied — instead of the plain due amount
the OCA module asks for.

## Why

A CashDro can only give change with the coins it holds. When the PoS is
configured with a cash rounding (`pos.config.cash_rounding`, typically to 0.05
so that 1 and 2 cent coins are not needed), asking the drawer for the unrounded
due leaves it trying to return change it does not have.

Core already computes that amount: `PosOrder.getDefaultAmountDueToPayIn()` is
what a payment line defaults to when it is created. We simply reuse it, so the
drawer is asked for exactly what the payment screen shows.

`shouldRound()` decides whether the rounding applies at all — it takes
`only_round_cash_method` into account, and the CashDro method is a cash one, so
in practice it is always true when a cash rounding is configured.

## How

One single patch on `PaymentCashdro.prototype._cashdro_amount()`, the hook
`pos_payment_method_cashdro_flow_fix` extracted for this. Everything else of the
OCA payment flow (request, acknowledge, polling, error handling) is untouched.

Two things this deliberately does **not** do:

- It does not touch the **reversals**. There the amount to send is the one of
  the line being given back, not the remaining of the order, and it is already
  the rounded figure that was collected. Rounding it a second time against the
  order total would ask the drawer to collect the total all over again.
- It does not touch `_cashdro_payment_url()`, which is what it patched until
  `18.0.1.1.0`. That method is shared by the payment and the reversal paths,
  which is exactly how the reversal bug above got in, and it collides with the
  fix modules that also patch it — the outcome then depending on the asset load
  order.

## Dependencies

Needs `pos_payment_method_cashdro_flow_fix` for the `_cashdro_amount()` hook,
and through it `pos_payment_method_cashdro_fix`: without them the OCA module
does not work on 18.0 at all, so there is nothing to round.

## Testing

There are no automated tests — the flow needs a CashDro answering on the
network. To check it by hand, configure a cash rounding of 0.05 on the PoS, take
an order to a total that is not a multiple of 0.05 (e.g. 17.43) and confirm the
drawer asks for 17.45. See the `USAGE` of
`pos_payment_method_cashdro_flow_fix` for how to read a failure.