As of ODK Collect v1.23, all values are sent to Google Sheets from Collect as raw values. That means Google Sheets will not try to apply any kind of formatting. When you edit a cell, you will see a tick before the value (e.g. '1-2-3 rather than 1-2-3). You can perform calculations with those values as you normally would and you can apply a format (e.g. currency, date) to select columns yourself if you would like.