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 $84.89   11.140%   $94.3467   $94.35   $94.35   $94.30  
  Purchase #2 $179.31   12.693%   $202.0698   $202.07   $202.05   $202.10  
  Purchase #3 $119.86   5.340%   $126.2605   $126.26   $126.25   $126.30  
  Purchase #4 $225.93   4.500%   $236.0969   $236.10   $236.10   $236.10  
  Purchase #5 $148.32   11.312%   $165.098   $165.10   $165.10   $165.10  
  Purchase #6 $22.70   8.749%   $24.686   $24.69   $24.70   $24.70  
  Purchase #7 $156.33   6.271%   $166.1335   $166.13   $166.15   $166.10  
  7 purchase totals = $937.34       $1,014.6914   $1,014.70   $1,014.70   $1,014.70