The ADXL345 doesn't specify sampling rate tolerance in the datasheet. For our application, we have been using the chip to detect the frequency content of the motion. Experimentally comparing two boards (both are identical and running identical firmware on an MSP430, communicating with the ADXL345 over SPI), I am seeing about 5% variance in the sampling frequency when both chips are configured at 200Hz. This seems like a large variance, is it in the expected range?
If the variance in sampling frequency is expected to be 5% (or more), we may need to migrate to a different accelerometer.