Yotta adds up all of your fractional/decimal bonus tickets and keeps them on record. As soon as those values add up to a whole number (1.0), you will be awarded a ticket.
For example, if you have 0.8 tickets and you make a $2 purchase, you will be awarded an additional 0.2 tickets, which adds up to 1 whole ticket.
Any leftover fractional bonus tickets leftover from one week will carry forward to the following week. For example, if you have 8.2 tickets one week, all 8 tickets will be used the following week and you will still have 0.2 bonus tickets as your starting bonus ticket balance the following week.