I wish to preserve this file for later generations. I have no technical know how to do this, any help would be greatly appreciated. Thanks.
1) Do you want to place this file as one piece? (This is not possible today)
2) Do you agree if the data in this file will be split for several (a lot number) pieces?
3) How much can you pay for it? (Today 1kb costs 0.00001...0.0001 btc. So, 5 mb is not very expensive, but not free)
This is actually insanely expensive. 1mb is 1000 kb, so that would be multiplied by 5000, so would be 0.5 btc, about 150 US dollars, to store one file...
The purpose of this actual bitcoin blockchain is not to "store" a large file, but only a max. of 40 byte of data (like someone has said in the previous posts). If the OP wants to store 5 Mb in one transaction then it will be impossible for the moment (due the limit of the block size ~ 1 MB) maybe in the future if the block size will rise to 10 or 20 MB someone can start "to think" about this function.
Remember that your file will be on each device/pc that has downloaded the entire blockchain (so it could be better to protect it with a password, but if the OP wants to save a file on the bitcoin blockchain then it means he want that information will be "public").