Here are some examples of how "in for a penny, in for a pound" can be used in sentences:

• I know this project is going to be difficult, but we've already spent a lot of time and resources on it. I say we're in for a penny, in for a pound, and we should see it through to the end.
• She was hesitant to invest more money in the business, but her partner convinced her that they were already committed and should go all in. In for a penny, in for a pound, he said.
• At first, I was only going to attend the conference for one day, but then I saw the full schedule and realized I wouldn't want to miss any of the sessions. So I figured, in for a penny, in for a pound, and decided to attend the whole thing.
• He was nervous about traveling so far for the job interview, but he had already invested so much time in preparing and researching the company. In for a penny, in for a pound, he thought, and booked the plane ticket.
• The renovations were already over budget, but they realized that the original plan wasn't going to work and they needed to make some additional changes. In for a penny, in for a pound, they decided, and made the necessary adjustments.