Roll-Up Summary currency fields on Accounts and Opportunities Not Available

Roll-Up Summary currency fields on Accounts and Opportunities Not Available

With Advanced Currency Management enabled Currency type fields are not available since fields to Aggregate in Accounts, Opportunities, and Custom Objects related to either Accounts or Opportunities. 

WorkAround:

Steps:

1. Create a custom number field with the same parameters as the currency field you want to summarize on the child object. 

2. Create a workflow rule on the child object : 

Evaluation Criteria: created, and every time it’s edited. 
Criteria: Created Date NOT EQUAL TO leave it blank 

3. Create a field update : 

Field to Update: The field created in step 1 
Re-evaluate Workflow Rules after Field Change: TRUE 
Choose: Use a formula to set the new value
Formula Value: Enter the API name for the currency field you want to summarize

4. Activate the workflow

5. Create a Roll-Up summary field on the Opportunity object : 

Summarized Object: Child Object 
Field to Aggregate: The number field created in Step 1 

6. Create a formula field on the Opportunity object : 

Formula Return Type: Currency 
Decimal Places: Enter the same number of decimal places as the field you originally wanted to summarize 
Formula: Enter the API Name of the field created in step 5

Reference(s): https://help.salesforce.com/