Pay sales tax with the Retail Sales Tax Return For Occasional Sales (DR 0100A) on the tangible personal property included in the purchase of the business by the 20th day of the month following the sale.
So, to avoid pregnancy she has to better avoid unprotected sexual intercourse in this period. The rest of the days i.e., starting from menstruation to the 10th day and again from 21st day up to menstruation are the safe days or the safe period to avoid pregnancy.
Everyday safety I wrote recently about bells and whistles in safety (https://safetyrisk.net/bells-and-whistles-and-due-diligence/) and how easily Safety is seduced into some delusional campaign of heroes and nirvana. One of the core messages of safety ought to be that there is not utopia and no nirvana.