I live in Canada. VTI and VUN are both US total market index funds through Vanguard. VTI is the American version, VUN is the Canadian version.
VTI has an MER of 0.04% but the dividends are subject to a 15% foreign withholding tax, and you need to pay for currency conversion. Conversely, VUN has an MER of 0.16% and no taxes on dividends (other than capital gains).
If my bank charges 15 basis points for currency conversion to buy VTI, does it still make sense to buy VTI assuming I'm holding it for more than 3 years since the cumulative cost of VTI would be 0.15% + 0.15% + (3 x 0.04%) compared to (3 x 0.16%)?