Are commercial foods adjusted for integer cooking times?

No. Pasta certainly can be varied by 1-2 minutes depending on the degree of bite desired (assuming the commercial, dried variety). Furthermore, height above sealevel determines air pressure and the boiling temperature of water, which further complicates things.

For microwaving, a similar problem occurs with power: not all microwaves have the same effective power, which means that you can't have an integer number of minutes of cooking time. In fact, if you see 600 W : 8 minutes, 1000 W : 5 minutes, you already know that they're rounded numbers (600*8 = 4800; 1000*5 = 5000, ignoring the larger heat loss in the first case)

[edit] A bit of math on the back of a napkin suggests that even at a fixed altitude, the difference between high and low air pressure is significant enough. No, they're not adjusting the ingredients to come up with an integer number. Besides, it'd be far easier to vary the thickness a bit.

The person writing the words on the pack is a marketing person. They probably don't know what an integer is, let alone how to cook the intended contents

Check the ingredient list, feel the dryness of the product, and work it out from your own experiences

As mentioned, the number of other variables involved would make any more accurate timing guidelines irrelevant. In fact, to within a minute is a fairly pointless. If you don't have one, try getting an oven thermometer and see just how accurate your oven thermostat is. It's a fun game!

@Yossarian really? I nearly always find pasta cooking times to be overestimated. Not as bad as most meat/fish times from supermarket produce, but normally about a minute or two too long. Are you saying you cooke penne (for example) for over 22-26 minutes? You don't live up a mountain do you?