Round back to nearest Tuesday or Friday

[WiscCard]

I'm trying to calculate a departure date for a shipping spreadsheet. Basically we take the delivery date, subtract 5 business days, then round backwards to the previous Friday or Tuesday.
I have a formula that is working if the delivery date falls on a Tuesday or Friday. If it doesn't, it is not rounding backward properly. Here is a table of the delivery dates and the date I need excel to calculate.
I am currently using the formula "=WORKDAY.INTL(A1,-5,1,1011011)"

DLV DATE DLV DAY DEPARTURE DATE DEPARTURE DAY
02/12/2016 Fri 25/11/2016 Fri
05/12/2016 Mon 25/11/2016 Fri
06/12/2016 Tue 29/11/2016 Tue
12/12/2016 Mon 02/12/2016 Fri
13/12/2016 Tue 06/12/2016 Tue
13/12/2016 Tue 06/12/2016 Tue
15/12/2016 Thu 06/12/2016 Tue
15/12/2016 Thu 06/12/2016 Tue
15/12/2016 Thu 06/12/2016 Tue
16/12/2016 Fri 09/12/2016 Fri
16/12/2016 Fri 09/12/2016 Fri
16/12/2016 Fri 09/12/2016 Fri
20/12/2016 Tue 13/12/2016 Tue
20/12/2016 Tue 13/12/2016 Tue
20/12/2016 Tue 13/12/2016 Tue
20/12/2016 Tue 13/12/2016 Tue
10/01/2017 Tue 03/01/2017 Tue
17/01/2017 Tue 10/01/2017 Tue
17/01/2017 Tue 10/01/2017 Tue
17/01/2017 Tue 10/01/2017 Tue
20/01/2017 Fri 13/01/2017 Fri
31/01/2017 Tue 24/01/2017 Tue
31/01/2017 Tue 24/01/2017 Tue
14/02/2017 Tue 07/02/2017 Tue

 

[Special-K99]

Cant you just do this?
Given a date A1 then the previous Friday or Tuesday would be

=A1-LOOKUP(WEEKDAY(A1),{1,2,3,4,5,6,7},{2,3,7,1,2,7,1})

 

[WiscCard]

Cant you just do this?
Given a date A1 then the previous Friday or Tuesday would be

=A1-LOOKUP(WEEKDAY(A1),{1,2,3,4,5,6,7},{2,3,7,1,2,7,1})

Thanks, that does work once I modify slightly to account for the 5 business days of transit.
=A1-7-LOOKUP(WEEKDAY(A1),{1,2,3,4,5,6,7},{2,3,0,1,2,0,1})

 

[WiscCard]

Hi Special-K99,
Can you please help me understand the last part of your formula? {1,2,3,4,5,6,7} is Sunday to Saturday I believe, but then the last part? This will help me do this myself if I have to edit. Thank you.