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 $88.36   7.627%   $95.0992   $95.10   $95.10   $95.10  
  Purchase #2 $234.75   11.230%   $261.1124   $261.11   $261.10   $261.10  
  Purchase #3 $235.44   9.490%   $257.7833   $257.78   $257.80   $257.80  
  Purchase #4 $154.29   6.324%   $164.0473   $164.05   $164.05   $164.00  
  Purchase #5 $160.56   4.464%   $167.7274   $167.73   $167.75   $167.70  
  Purchase #6 $175.67   12.487%   $197.6059   $197.61   $197.60   $197.60  
  Purchase #7 $54.94   12.240%   $61.6647   $61.66   $61.65   $61.70  
  7 purchase totals = $1,104.01       $1,205.0402   $1,205.04   $1,205.05   $1,205.00