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 $185.61   5.386%   $195.607   $195.61   $195.60   $195.60  
  Purchase #2 $87.34   7.555%   $93.9385   $93.94   $93.95   $93.90  
  Purchase #3 $84.71   5.334%   $89.2284   $89.23   $89.25   $89.20  
  Purchase #4 $241.84   8.618%   $262.6818   $262.68   $262.70   $262.70  
  Purchase #5 $47.40   5.797%   $50.1478   $50.15   $50.15   $50.10  
  Purchase #6 $193.96   6.813%   $207.1745   $207.17   $207.15   $207.20  
  Purchase #7 $235.67   7.275%   $252.815   $252.82   $252.80   $252.80  
  7 purchase totals = $1,076.53       $1,151.5930   $1,151.60   $1,151.60   $1,151.50