Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
  Case Tag  
Price  
Sales  
Tax %  
Raw Total  
Incl. Sales Tax  
Rounded  
to Penny  
Rounded  
to Nickel  
Rounded  
to Dime  
  Purchase #1 $118.89   5.786%   $125.769   $125.77   $125.75   $125.80  
  Purchase #2 $100.36   11.300%   $111.7007   $111.70   $111.70   $111.70  
  Purchase #3 $180.57   4.376%   $188.4717   $188.47   $188.45   $188.50  
  Purchase #4 $113.33   5.599%   $119.6753   $119.68   $119.70   $119.70  
  Purchase #5 $153.59   4.590%   $160.6398   $160.64   $160.65   $160.60  
  Purchase #6 $223.60   5.225%   $235.2831   $235.28   $235.30   $235.30  
  Purchase #7 $237.55   6.674%   $253.4041   $253.40   $253.40   $253.40  
  7 purchase totals = $1,127.89       $1,194.9437   $1,194.94   $1,194.95   $1,195.00