Need to adjust the last bill line using groovy script

Summary:

When we do adjustment on covered level manually the billing lines generated has a small fractional amount less than actual value.

Example on covered level adjustment is updated to 1000$ and it is monthly billing the bill lines are 83.33 each. The total contract value becomes 999.96.

Content (please ensure you mask any confidential information):

Need to write a groovy script on a button click so that the last billing line can get the adjusted amount.

Version (include the version you are using, if applicable):

25C

Code Snippet (add any code snippets that support your topic, if applicable):