The "big round numbers" (e.g. EUR/USD 1.2800, USD/JPY 99.00) are natural levels of support and resistance. These are psychological levels (easy for humans to think about), as well as "lazy" levels when setting entries or profit targets. Additionally, the importance of the big round numbers has also increased because they are used for options barriers levels.
As a result, a lot of orders are placed around these levels.
The “Big Round Numbers” indicator is a very simple but effective indicator that high-lights these levels on your charts. The indicator can be set to show levels of 50, 100, 250, 500 and 1000 pip increments. Of course, colours and line widths are customizable.
The indicator is available from my blog. See here for more information.