PHP SimpleXMLElement对象 - 检查子行项目值

I'm working with a SimpleXMLElement Object and retrieving amounts for invoices, some of which contain several line items each with a zero dollar value. I now need to skip any invoices where each of the line items has a zero dollar value. Here's an example:

    [11] => SimpleXMLElement Object
(
    [Contact] => SimpleXMLElement Object
        (
            [ContactID] => gzd123456
            [Name] => Acme Inc.
        )

    [Date] => 2017-04-13T00:00:00
    [DueDate] => 2017-04-13T00:00:00
    [Status] => PAID
    [LineAmountTypes] => Inclusive
    [LineItems] => SimpleXMLElement Object
        (
            [LineItem] => Array
                (
                    [0] => SimpleXMLElement Object
                        (
                            [Description] => Stock on hand
                            [UnitAmount] => 0.00
                            [TaxAmount] => 0.00
                            [LineAmount] => 0.00
                            [Quantity] => 1.0000
                        )

                    [1] => SimpleXMLElement Object
                        (
                            [Description] => Cost of goods sold
                            [UnitAmount] => 0.00
                            [TaxAmount] => 0.00
                            [LineAmount] => 0.00
                            [Quantity] => 1.0000
                        )

                )

        )

    [UpdatedDateUTC] => 2017-04-12T22:55:02.657
    [CurrencyCode] => AUD
    [Type] => ACCPAY
    [HasAttachments] => false
)

I'm looping through each invoice like this:

foreach ($invoices->Invoices->Invoice as $invoice) {

then looping through each invoice line item like this:

foreach ($invoiceLineItems->LineItem as $invoiceLineItem) {
    $LineAmount = $invoiceLineItem-> LineAmount;
}

which is working fine, but I would like to short circuit the foreach ($invoiceLineItems->LineItem as $invoiceLineItem) { if possible where all LinteItem>LineAmount values are '0.00'. Is it possible to query all the LineItems at once to see if they are all equal to '0.00'?