I created my own custom Average Booster report in BLS-2018 and compared it to the LeagueSecretary.com upload for the same league and I found the same to be the case. BLS apparently calculates the minimum to raise, say 152.6 to 153.0. LeagueSecretary apparently calculates the identical fraction one pin higher. It appears to be calculated by the website, but I can't say that absolutely.
You do have the ability to include the Average +1 number with your standings sheet, and if you upload that to LeagueSecretary, it will display that without anyone having to access that side report. Now I do know that Scott Scriver (webmaster of the LeagueSecretary site) does periodically look here, and you may get a response from him on this one day.
If you want to include the Average +1 number on your standings and need assistance, please let us know.
Always check, download, and install the most recent update of your software to ensure that issues may have been corrected.