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 $167.69   8.530%   $181.994   $181.99   $182.00   $182.00  
  Purchase #2 $225.51   11.614%   $251.7007   $251.70   $251.70   $251.70  
  Purchase #3 $24.53   10.250%   $27.0443   $27.04   $27.05   $27.00  
  Purchase #4 $228.64   3.108%   $235.7461   $235.75   $235.75   $235.70  
  Purchase #5 $186.55   5.532%   $196.8699   $196.87   $196.85   $196.90  
  Purchase #6 $204.63   3.134%   $211.0431   $211.04   $211.05   $211.00  
  Purchase #7 $53.66   6.709%   $57.26   $57.26   $57.25   $57.30  
  7 purchase totals = $1,091.21       $1,161.6581   $1,161.65   $1,161.65   $1,161.60