round up vs sign up

round up

verb
  • To collect or gather (something) together. 

  • To gather (cattle) together by riding around them. 

  • To round (a number) to the smallest integer that is not less than it, or to some other greater value, especially a whole number of hundreds, thousands, etc. 

  • To arrest or detain a group of people without individualized suspicion or cause, often as a form of targeted persecution. 

sign up

verb
  • To agree to purchase some good or service. 

  • To add one's own name to the list of people who are participating in something (including amateur, but not professional, teams) 

  • To add a name to the list of people who are participating in something. 

How often have the words round up and sign up occurred in a corpus of books? (source: Google Ngram Viewer )