PHP - custom shopping cart changes for pet hotel site

PET DAYCARE/HOTEL site rebuild – NEW under construction website. Not a commercial cms of any type, everything is custom php. We did not build original site...just helping to complete project. Lots of site errors and many additions coming. These are just the first priority ones.. The site are two intigrated shopping carts -- DAYCARE and HOTEL, both with some different problems. Task 1 - DAYCARE reservation time not updating when changed by user: Selecting <UPDATE> button - Reservation time always changes back to 7:00 am. (This reservation time selection works if you select the HOTEL page instead of DAYCARE, so some code from the HOTEL may help) Task 2 - Both HOTEL and DAYCARE date selecting - Popup shows unavailable days in wrong format: Reservation calendar Pop up box dates are in European style (day-month), this needs to be month-day. Task 3 - HOTEL only issues, blocked(unavailable) days not appearing on calendar: Blocked dates in the Admin are not blacked out on the front-end calendar for HOTEL. (They are blacked out for daycare blocks, just not hotel.) Task 4 - Cart totaling error, averaging (I think) instead of totaling each item separately: The hotel/daycare shopping cart check out is not totally numbers correctly. It is adding the daily prices and using an average or something to get the total. The pricing formula should be (29 + 25 + 25 + 15 + 15 + 15) = 124.00, NOT ((29 + 25 + 25 + 15 + 15 + 15) / 6) X 6 = 123.99. DETAILED EXAMPLES: Three shopping cart check outs, Hotel and Daycare Halfday and Full Day All 3 checkout are charging incorrectly. Pet owner books... Hotel: 7 pets... For 1 night, $53 1st pet, 6 additional pets at $50 each, should = $353 But website charges $353.01 Daycare Full Day: 3 pets... For 1 day, $29 1st pet, 2 additional pets at $25 each, should = $79 But website charges $78.99 Daycare Full Day: 6 pets... For 1 day, $29 1st pet, 2 additional pets at $25 each, should = $154 But website charges $154.02 If you check out with other quantities of pets, the cart seems to add up properly. It seems to be doing some sort of averaging. For billing the client, I need to know why this is doing this so I can trace if it was because of something we did to the site. Once this is corrected on the new site and is tested and confirmed, the same correction needs to the current live site (Same server, just a different folder). --- When testing, be careful in the Admin, the prices and calendar are connected to the current live site. Many more tasks coming once these are complete.