Basic rounding scheme to avoid sampling/rounding errors. From PIC24 but pseudo-code enough to be ported.

roundingScheme.c

void SampleADC() {
    /* Wait till interrupt says samples are ready */
    while (!AD1CON1bits.DONE);

    /* Assign buffer values to temp variables for processing */
    tempPot = ADC1BUF0;
   
    /* Set threshold values to avoid fluctuating rounding errors */
    int potThresh = 25;
    
    /* Calculate 1024 scaled value for current volume */
    cv = currentPot * 32;

    /* Check threshold ranges and update if necessary */
    if ((tempPot <= (cv - potThresh)) && (currentPot != 0)) {
        /* Volume has changed one step lower */
        currentPot--;
        
    } else if ((tempPot >= (cv + potThresh)) && (currentPot != 31)) {
        /* Volume has changed one step higher */
        currentPot++;

    } else {
        /* No change in volume */
       
    }
}