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 $55.34   11.563%   $61.739   $61.74   $61.75   $61.70  
  Purchase #2 $95.30   7.347%   $102.3017   $102.30   $102.30   $102.30  
  Purchase #3 $65.46   11.819%   $73.1967   $73.20   $73.20   $73.20  
  Purchase #4 $178.71   3.346%   $184.6896   $184.69   $184.70   $184.70  
  Purchase #5 $22.88   5.542%   $24.148   $24.15   $24.15   $24.10  
  Purchase #6 $141.72   4.258%   $147.7544   $147.75   $147.75   $147.80  
  Purchase #7 $125.42   4.798%   $131.4377   $131.44   $131.45   $131.40  
  7 purchase totals = $684.83       $725.2671   $725.27   $725.30   $725.20