Most tenders these days are conducted on line. This means that the tender deadline is applied automatically. If the system shows that your bid was submitted a split second after the deadline you will be deemed to have missed it, and all your hard work will come to naught!
My philosophy is to avoid missing the tender dealine as an absolute priority.
One tip is to check if you can submit a bid prior to the deadline and subsequently edit it. In my experience this is usually the case. If this is so then you could submit an early draft of your bid, and edit it later – in the knowledge that, whatever else happens, you won’t miss the deadline.