In our country (Zimbabwe), trade in the local currency (ZWL$) is considered separately from trade in foreign currency (usually US$) for our tax purposes. We now have separate accounts with the tax authority for the two currencies (see also this topic). This means that we don’t include the foreign exchange gains/losses in our submissions to the tax authority. They will not consider a foreign exchange loss to be a deductible expense, and we will not be taxed on foreign exchange gains.
I understand, however, that the principles of double-entry accounting require that the foreign exchange gains and losses are displayed in the profit and loss statement so that the books are balanced when everything is converted to the base currency. It is easy enough for us to omit them in our filings, which is what our accountant has advised.