This mode is very important for those who wants to charge commission based on the sales of the vendor, so say suppose you want to create the following rule for vendor commission:
70% commission upto sales $1000
75% commission upto sales $2000
80% commission upto sales $5000
85% commission more than $5000
You can select the commission Type either as percentage, fixed or percentage+ fixed depending upon the rule you want to implement. Ensure that you do not create conflicting rules while configuring the slab.