Unfortunately, there is no crypto price calculator feature on Coinmetro, so this will need to be done by yourself manually.
You can find the prices that you bought cryptocurrencies for within your Coinmetro transaction history. You'll then need to enter these into an external average crypto price calculator, such as the Average Crypto Price Calculator by Leverage Trading.
You can find your Coinmetro Transaction History by following these steps:
From your Wallet, click on "Transactions". Here, you can select assets, define a date range, and select different transaction types
You can also download your balance history by scrolling down to the bottom of the page, clicking on 'Download', and then selecting one of the available format options:
PDF Format (beta)
Generic CSV Format
Koinly CSV Format
CoinTracking CSV Format.