Charge $297 per hour and not $300.

Here's a fascinating article in Scientific American titled Why Things Cost $19.95 that discusses the psychological impact certain prices have over others. If you've always wondered why we see odd prices so often ($19.95 vs. $20.00), the article gives the answer. Two University of Florida marketing professors studied how consumers relate a ticketed price to the perceived wholesale "cost" of a good or service:

There were three scenarios involving different retail prices: onegroup of buyers was given a price of $5,000, another was given a priceof $4,988, and the third was told $5,012. When all the buyers wereasked to estimate the wholesale price, those with the $5,000 price tagin their head guessed much lower than those contemplating the moreprecise retail prices. That is, they moved farther away from the mentalanchor. What is more, those who started with the round number as theirmental anchor were much more likely to guess a wholesale price that wasalso in round numbers. The scientists ran this experiment again andagain with different scenarios and always got the same result.

Why would this happen? As Janiszewski and Uy explain in the Februaryissue of Psychological Science, people appear to create mentalmeasuring sticks that run in increments away from any opening bid, andthe size of the increments depends on the opening bid. That is, if wesee a $20 toaster, we might wonder whether it is worth $19 or $18 or$21; we are thinking in round numbers. But if the starting point is$19.95, the mental measuring stick would look different. We might stillthink it is wrongly priced, but in our minds we are thinking aboutnickels and dimes instead of dollars, so a fair comeback might be$19.75 or $19.50.

I'd really recommend you read the entire article, but the initial takeaway for me is this: If you want clients to believe your rate (or set price for a given service) is close to your actual cost, price in odd numbers.