How to calculate tax/tip when bartering

UPDATE: I have a new easier way to calculate tax/tip posted here.

We’ve already discussed in the past how valuable it is to have restaurant barter partners. As such it is important to act as a good “barter ambassador” and make sure you tip well. The last thing you want is for a restaurant to quit bartering because their waitstaff complain that barter folks are bad tippers. That being said I have to be honest and say that even when I want to tip well often it is tough to be sure my math is correct when I’m calculating the tip. I know it’s not rocket science but there are a couple things that make barter tipping more complicated than a “normal” tip. First off, most restaurants want both tax and tip in cash. To complicate things more, many times you are paying with script that doesn’t add up evenly to the barter portion of the bill. So with all this in mind, here is the method that I’m currently using to calculate how much barter and cash I should leave on the table:

Calculate what the total for the meal, tax and tip would be in cash and remember that number. For those of you that are memory-challenged like myself feel free to write that down.
Pay the meal portion of the bill in barter. Often barter script comes in 10 dollar denominations. To make the calculation easier it’s my recommendation to never round up with your use of barter script. Round down. Step three addresses covering the difference in cash.
Subtract the difference between the number you came up with in step 1 and the amount of script you left in step 2 and that’s what you leave in cash.

Here’s an example: Your meal was $55 and tax was $5.

$60 x 120% = $72 (for a 20% tip….I normally tip on the tax too…is that what everybody else does?)
$50 in script (round the $55 down to $50)
$72 – 50 = $22 in cash

That’s not so hard is it? This method is simple enough that you can do it accurately and quickly every time. The common place to get tripped up is if you round up with your barter. There is nothing wrong with doing that, but then you have to remember to add in the extra barter in step 3 that shouldn’t count toward your tax and tip.

Here’s an example if you round up: Your meal was $55 and tax was $5

$60 x 120% = $72 (that’s the same as above)
$60 in script (round $55 up to $60 so you’re leaving an extra $5 in barter)
$72 – 60 +5= $17 in cash (You are adding back in to make up for the 5 extra barter dollars you gave in step 2 that don’t count toward cash and tip)

In this example rounding the barter up is actually a better deal for you. You are paying $5 in barter to save $5 in cash. It’s pretty easy to mess up the math though. If you don’t remember to add back in the extra $5 you only end up leaving $12 in cash, $5 of which was tax. That leaves only $7 for your tip on a $60 bill.