GET your REST data and store in a PowerShell object:

$Users = Invoke-RestMethod -Uri "<http://jsonplaceholder.typicode.com/users>"

Modify many items in your data:

$Users[0].name = "John Smith"
$Users[0].email = "[email protected]"
$Users[1].name = "Jane Smith"
$Users[1].email = "[email protected]"

POST all of the REST data back:

$Json = $Users | ConvertTo-Json
Invoke-RestMethod -Method Post -Uri "<http://jsonplaceholder.typicode.com/users>" -Body $Json -ContentType 'application/json'