public IActionResult CalculateTotal([FromBody] CalculateTotalModel model) { if (model.Roster.Count == 0) { return(Ok(0)); } var usd = model.Roster.Aggregate( 0d, (total, item) => total + _currencyConverter.ConvertToUSD(item.CurrencyAbbrv, item.Value)); var convertedTotal = _currencyConverter.ConvertFromUSD(model.TargetCurrencyAbbrv, usd); return(Ok(Math.Round(convertedTotal, 2))); }