It is best to use TI (Texas Instruments) boost charge pump device TPS60110, its peripheral components only need four small capacitors (2.2μF two, 15μF one, 33μF one., the voltage can be 10V). Input voltage range 2.7~5.4V, self-consumption (static current.) Only 2.8mA, output 5V\/300mA.
This is to increase the 3V voltage to 5V with what boost chip is better reason