Two main patterns: (1) Used alone at the end of a sentence to express resignation: 也罢 = 'fine then, let it be.' (2) Reduplicated A也罢B也罢 to mean 'whether A or B' - similar to 也好...也好.
register
More literary and dramatic than everyday speech. In casual conversation, people would say 算了 or 随便吧 instead.
