I am not a SQL developer by any means. I have a application to build for a Valet company that will require a laptop on site with no internet connectivity to function locally. There will be about 15 locations that all operate independently. After the day is done, the laptops will connect to the internet and upload all data to a hosted SQL server on the internet for centralized data storage and reporting. After a successful upload, the client database will be purged and start fresh the next day. Should this be doe with MYSql on the client and SQL server at the data center? I have some people recommending Progress database but it is expensive. I am out of my element when it comes to syncing db's so any advise is appreciated. Thanks-

Can't you use SQL Server Express? How big is the DB?

Merge replication seems to be suitable for your scenario. Since SQL Express can be only a "subscriber", you can use it on the laptops. At the datacenter, you can use a "paid" edition, such as "standard".