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 $69.67   9.132%   $76.0323   $76.03   $76.05   $76.00  
  Purchase #2 $174.68   4.218%   $182.048   $182.05   $182.05   $182.00  
  Purchase #3 $106.64   12.311%   $119.7685   $119.77   $119.75   $119.80  
  Purchase #4 $175.28   12.209%   $196.6799   $196.68   $196.70   $196.70  
  Purchase #5 $174.29   12.479%   $196.0396   $196.04   $196.05   $196.00  
  Purchase #6 $226.66   9.108%   $247.3042   $247.30   $247.30   $247.30  
  Purchase #7 $52.53   6.805%   $56.1047   $56.10   $56.10   $56.10  
  7 purchase totals = $979.75       $1,073.9772   $1,073.97   $1,074.00   $1,073.90