Alright, so let's get started.
First, what you'll focus on doing is rounding each item to the nearest whole dollar. Remember, you have yourself and 3 friends. So:
Movie tickets- $8 x 3 = $24
Medium Popcorns- $3 x 3 = $9
Medium Soft Drinks- $3 x 3 = $9
So, altogether: $42
If you want to include tax as well, go for it. So maybe $45?