We found a bug when using Text() function. My purpose is to show a in

You can use the following function.
dollar(25000.01,2)

It will give you the desired output.

Thanks for your suggestion. This is a solution we are going to apply.
But is it an appian bug?

I would rely on fixed function for rounding the number to certain number of decimal places and add commas to numeric values if required. It gives me correct result always. Text function works perfectly fine if you have correct format in place. Format may or may not work for some scenarios such as the one you mentioned.

For instance, this expression gives me exact $16,383.30.
dollar(
fixed(16383.3,2,false()) /**Round upto 2 decimal places and show commas*/
)

Be aware that if you start going into very large numbers or very small numbers the values may be converted to scientific notation by Appian depending on which functions you're using.