1. A currency counting and evaluation device for receiving a stack of currency bills, rapidly counting and evaluating all the bills in the stack, and then re-stacking the bills, said device comprising a feed mechanism for receiving a stack of currency bills and feeding said bills in the direction of the narrow dimension of the bills, one at a time, to a feed station, a bill transport mechanism for transporting bills, in the direction of the narrow dimension of the bills, from said feed station to a stacking station, at a rate in excess of about 800 bills per minute. a stationary optical scanning head located between said feed and stacking stations for scanning a preselected segment of a central portion of each bill transported between said stations by said transport mechanism, said scanning head including at least one light source for illuminating a strip of said preselected segment of a bill, and at least one detector for received reflected light from the illuminated strip on the bill and producing an output signal representing variations in the intensity of the reflected light, sampling said output signal preselected intervals as a bill is moved across said scanning head in the direction of the narrow dimension of the bill, a memory for storing characteristic signal samples produced by scanning said preselected segments of bills of different denominations with said scanning head and sampling said output signal at said preselected intervals, and signal processing means for receiving said signal samples and (1) determining the denomination of each scanned bill by comparing said stored signal samples with said output signal samples produced by the scanning of each bill with said scanning head, (2) counting the number of scanned bills of each denomination, and (3) accumulating the cumulative value of the scanned bills of each denomination.