FX conversion on AP invoice between invoice currency and local tax reporting currency

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The scenario is as below

Invoice currency: USD

Payment currency: USD

Ledger currency: USD

Tax reporting currency: SGD (for a SG registered company)

The supplier has provided a designated conversion rate between the invoice currency (USD) and tax reporting currency (SGD), which will be used to translate the VAT amount to tax reporting currency (SGD) for tax filing purposes. Is there anywhere on the invoice where we can store this conversion rate?

Per our understanding, the invoice conversion rate is to convert between invoice currency and ledger currency for journal booking, so this would not be a valid field for our requirement.