It's not so easy to mint coins. Canadian law says: If you want to destroy money, then burn banknotes. Don't destroy metal coins.
In fact, in Canada, it is legal to burn banknotes. (Note: In the U.S., it's illegal.)
A) Most people redeem ma'aser sheni (second tithe) using a coin. If you purchase imported Israeli produce, are you allowed to redeem ma'aser sheni using a banknote — even though a banknote is not a coin?
B) The Wikipedia article "Burning money" says that burning paper money helps control inflation. (Destroying coins might be different.) If you burn a $5 bill, you will increase the collective wealth of your fellow countrymen by about $5. Will you have fulfilled the commandment of bi'ur ma'asrot even though you've just enriched your countrymen?
Warning: If you want to burn the new Canadian plastic banknotes, consult a doctor first. Ask about the health effects of the fumes which will result.
Note: The vast majority of people who answer questions here are educated laypeople, not rabbis. In matters as complex as this, don't rely on laypeople. Instead, ask a local Orthodox rabbi, for many reasons.