Last year I installed an AMD Firepro W4100 in a machine for someone that is used with 4 large screens for financial trading purposes and some Photoshop (but no gaming). It's equipped with 4 mini Display Port plugs (can be converted to DVI or HDMI with suitable leads or adaptors). At the time it seemed one of the more cost effective ways to run four screens, doesn't draw much power, and it suited his needs fine.
Not saying it's the only way. For example a cheaper option is a Radeon R7-250X which according to AMD supports 4 displays using the built in ports (1 x DisplayPort, 2 x DVI, 1 x HDMI) or up to 6 combined with a DisplayPort MST hub. Similar situation with the newer/higher spec Radeon R7-360.
This assumes you are running monitors with a digital connection (DVI, HDMI or Display Port). If you are using VGA only monitors you may struggle. Do check the exact configuration of the card before you buy, as there are different port combinations available within the same basic model of card.
The Firepro card runs off the PCIe slot only, and has low power requirements. The two Radeon's need a PCIe connector from the power supply as they draw more than 75w. However, they should be perfectly OK with a 460w power supply.
Video benchmarks are pretty irrelevant for running accounting software, any modern video card will have sufficient performance, you just need it to support your display configuration (and the GT 720 doesn't support 4 displays at all, if Nvidia's official specs are right).