Margin blending is a combination of higher and lower margin products to achieve an overall margin figure. It can be helpful in the high volume bar setting in order to increase efficiency and sales.
 
Margin blending is simple - you group similarly priced liquors together to have one price level. To gain your overall desired margin, you will make a little more on the lower priced items in the group, but a little less margin on the higher priced items in the group.
 
Most high volume bars will have 4 or 5 different price levels. To make things even faster, you could factor in the tax, so that the total amount due is a whole dollar amount (or at least to the quarter). This will allow your staff to spend less time making change and more time making drink, thus increasing capacity, efficiency, and revenue.
 
It will also help you as a manager because you won't need to supply the bar with change every five minutes. Also, your customer will likely appreciate not having to juggle a handful of pennies when their trying to enjoy their cocktail.