The dollar index dipped 0.2 percent to 98.841 .DXY after jumping as far as 99.332 the previous session.
The greenback had risen to a four-week peak of 111.780 yen on Wednesday before Trump's tax reform plans were announced. But it lost altitude as the tax plan details failed to inspire investors. The dollar was last higher 0.2 percent at 111.20 yen.
The euro rose 0.1 percent to $1.0913. The single European currency has had a good week, rising to a 5-1/2 month peak of $1.0951 on Wednesday, as the first round of the French presidential elections eased political risks.
Investors also waited for the European Central Bank's monetary policy decision on Thursday.