Azure Backup from 5 different locations

Azure Backup v2 (not to be confused with Azure Site Recovery) is priced per protected instance and based on the amount of Azure storage used.  A protected instance is a server, physical or virtual or database.  

If you are going to back up from five different physical locations, you will probably want to have an Azure Backup server in each physical location.  

Azure Backups are stored on the Azure Backup server's storage first, then Azure blob storage is used for backup retentions.  This allows for the fastest recovery times during restores.  

You could have all five locations use a single Azure Backup server and storage as the backup target if you wanted, just understand the network implications.  But you are not charged a fee for the Azure Backup server, you can have as many as you need for the best implementation.

Azure Backup pricing - FAQ

Azure Backup Documentation

If you have a good idea on how much storage and how many instances you are going to backup then you can build a good estimate of the monthly costs using the pricing calculator.

Azure Calculator for Azure Backup

I recommend using Windows Server 2016 for your on-premise Azure Backup server (MAB) it uses ReFS for your storage which greatly increases the compression and adds de-duplication both will speed up your backups and lower your spend on Azure storage.  

Also note, Azure Backup is available in the Central and South India regions at this time, not available in the West India region.

Azure Services per Region