Omp Amp Design for shifting a voltage range
The simplest way is to reverse your 0V-5V to 5V-0V in firmware and use a subtracting circuit: 







simulate this circuit &ndash; Schematic created using CircuitLab

Optionally, add another inverting amplifier afterward to get -2.5V to +2.5V for 0-5V in. 

The reference and resistor accuracy, and op-amp type will depend on your required precision. The op-amps will require a dual supply such as +/-5V, of course.