Using ZC version 1.3.9h and the latest USPS_2014_1030_K6 pluging. It seems to be working fine.
Is there a plugin or setting or something that will hide Shipping options based on cart total dollar amount? This cart uses USPS and Fedex. Because of tracking issues they want the cart not to show the USPS option if the cart value is over $75 US. I saw where there was a line in includes/modules/shipping/usps.php for it not to exceed $2499 US per box. Would it work if I changed that to 75 or 0075 per box in the lines needed. Or does more code have to be added to total the cart because per box could be considered per piece and you could put 50 items below $75 and never exceed the limit.
Here's where I mean:
'<ValueOfContents>' . number_format(2499 > 0 ? 2499 : 2499, 2, '.', '') . '</ValueOfContents>' .

Maybe change it to
'<ValueOfContents>' . number_format(0075 > 0 ? 0075 : 0075, 2, '.', '') . '</ValueOfContents>' .

Most of the products are not expensive, small, lightweight and usually ship in one box, envelope or whatever they can fit them in. They really don't use the weight or size feature in their shipping.

The code above is about halfway down all the coding on that page.