Great article written by an expert on small business year end tax deductions. Note that section 8 discusses how to handle business equipment deductions (like the cost of cash register or point of sale equipment): http://www.nolo.com/legal-encyclopedia/top-tax-deductions-small-business-30176-2.html
in mind payment for equipment purchases has to be made in 2012. I can think of many New Years Eves when a retail store, bar or restaurant would call me or stop by our office to pre-pay for a point of sale system. They needed to maximize their business equipment tax deduction and point of sale equipment makes for a great business equipment investment.
Section 10 of the article also talks specifically about to depreciate small business software expenses.