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 $119.83   4.796%   $125.577   $125.58   $125.60   $125.60  
  Purchase #2 $248.53   8.195%   $268.897   $268.90   $268.90   $268.90  
  Purchase #3 $109.77   8.869%   $119.5055   $119.51   $119.50   $119.50  
  Purchase #4 $28.53   11.115%   $31.7011   $31.70   $31.70   $31.70  
  Purchase #5 $178.92   4.247%   $186.5187   $186.52   $186.50   $186.50  
  Purchase #6 $231.69   8.627%   $251.6779   $251.68   $251.70   $251.70  
  Purchase #7 $187.56   8.498%   $203.4988   $203.50   $203.50   $203.50  
  7 purchase totals = $1,104.83       $1,187.3760   $1,187.39   $1,187.40   $1,187.40