Priority Insurance how to buy insurance for $100

[merrynbrite]

Priority gives $50 of free insurance, the package is worth $100 - do I have to buy a full $100 or just another $50 to have it fully insured?  

One poster said they click the buy insurance option and change the value to $49 for insurance (which is free) and this way they are able to have insurance valued at $99 - I have my doubts that this would work if one was to end up making a claim for $99.  It is a shame to pay more than one needs to for insurance.

Thanks in advance for any insights you have on this issue