## Explanation

The key to solving this problem is to realize that the solution requires a specific kind of rounding. We can't just round to the "nearest" .45 or .95 value. In fact, the first step is to round *up* to the nearest *half* dollar (.50). The second step is to subtract 5 cents ($0.05).

To round up to the nearest half dollar, we use the CEILING function, with the *significance* argument set to .5:

```
=CEILING(B5,0.5) // round up to next half dollar
```

This will round the original price up to the next half dollar. For example, $4.31 will become $4.50, and $5.72 will become $6.00. Importantly, if a price already ends in .00 or .50, it will remain unchanged (i.e. a price of $4.00 or $4.50 is not affected).

Once rounded, the formula simply subtracts 0.05 to get a .45 or .95 result. The formula in C5, copied down, is:

```
=CEILING(B5,0.5)-0.05
```

When B5 contains $17.01, the formula is solved like this:

```
=CEILING(B5,0.5)-0.05
=CEILING(17.01,0.5)-0.05
=17.50-0.05
=17.45
```

### About CEILING

CEILING is one of 8 rounding functions in Excel. You can use CEILING to do things like:

- Round numbers up to multiples of 25
- Round time up to 15 minute multiples
- Round materials up to the next whole unit

The MROUND function and FLOOR function can also round to a given multiple, but the behavior is different from CEILING: