I am getting this below error when I am trying to insert more than 10 records of opportunity and if the batch size is more than 10 through Data Loader. I have a after insert trigger and before update tigger on opportunity which updates the fields of oportunity. But this issue is not coming when I change the batch size to 4 in Data loader. Please let me know how can I resolve this issue.

Too many retries of batch save in the presence of Apex triggers with failures: when triggers are present partial save requires that some subset of rows save without any errors in order to avoid inconsistent side effects from those triggers

We are trying to create a field formula to calculate commissions based on down payment percentage. The IF formula is slightly too big. Any suggestions to make this formula fit?

IF(Down_Payment_Percent__c >= 0.1 && Down_Payment_Percent__c <= 0.2499, Amount *0.08,

IF(Down_Payment_Percent__c >= 0.25 && Down_Payment_Percent__c <= 0.4999, Amount *0.09,

IF(Down_Payment_Percent__c >= 0.5 && Down_Payment_Percent__c <= 0.7499, Amount *0.10,

IF(Down_Payment_Percent__c >= 0.75 && Down_Payment_Percent__c <= 0.9999, Amount *0.11,

IF(Down_Payment_Percent__c >= 1 , Amount *0.12,0)))))

Thanks