By definition, the act of accounting is the process of analyzing data, reporting it, and documenting financial transactions in a systematic and uniform way. This being said, the fact that accounting has exact methodologies by which the reporting and documenting is done precludes that it follows a pseudo scientific method. By scientific it does not mean that it follows the same procedure used in medical sciences, but that it follows a solid, concrete and effective series of steps that can be repeated by different people and still have the same results.
When it comes to quantities, amounts, and working with numbers in general it is imperative to have a system that proves to be exact and can be repeated with the same results. In that sense, accounting is a science.
However, as with every science, all of those who are successful and have a special gifted technique may define their talent as an art. That is, the act of accounting itself is not considered an art, but the process of accounting in a way that is unique an effective at the same time is certainly an artistic product.