curl --request GET \
  --url https://api.prime.coinbase.com/v1/entities/{entity_id}/conversion/fees

{
  "fees": [
    {
      "from_currency": "USDC",
      "to_currency": "USD",
      "net_conversion_volume_mtd": "12345678.90",
      "fee_tiers": [
        {
          "min_threshold": "10000000",
          "max_threshold": "150000000",
          "rate_bps": "5.0"
        }
      ]
    }
  ]
}