This is the 6486th most frequent Dutch word.
uitgerekend
"Uitgerekend" means "of all things" or "precisely."
In this sentence, 'uitgerekend' is used to express a specific emphasis on the unlikely or inconvenient timing (today).
Uitgerekend vandaag regent het de hele dag.
Of all days, it is raining all day today.
Here, 'uitgerekend' highlights surprise or emphasis on the specific choice (the most expensive gift).
Hij heeft uitgerekend het duurste cadeau gekozen.
He has chosen exactly the most expensive gift.
In this context, 'uitgerekend' emphasizes the irony or improbability that 'she', in particular, was tasked.