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 $84.31   13.327%   $95.546   $95.55   $95.55   $95.50  
  Purchase #2 $234.30   13.416%   $265.7337   $265.73   $265.75   $265.70  
  Purchase #3 $210.33   8.827%   $228.8958   $228.90   $228.90   $228.90  
  Purchase #4 $97.38   12.416%   $109.4707   $109.47   $109.45   $109.50  
  Purchase #5 $158.76   10.210%   $174.9694   $174.97   $174.95   $175.00  
  Purchase #6 $207.93   13.540%   $236.0837   $236.08   $236.10   $236.10  
  Purchase #7 $60.95   8.648%   $66.221   $66.22   $66.20   $66.20  
  7 purchase totals = $1,053.96       $1,176.9203   $1,176.92   $1,176.90   $1,176.90