I want to enable user to change the duration of PWM from 0 to 255, the number should be in minute and increase/decrease with two push buttons.

(X) x 255 / 60000 = minute

In above example each time plus button pressed value (X) will multiple by the numbers of button pressed.

if (plusButton == HIGH) {
    PWMduration += (X);
}

The nearest number i found is 235.29 which equals to almost 1 minute:

235.29 x 255 / 60000 = 0.9999

How can i round that number to 1? or is there any other alternative solution to calculate this?