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 $73.33   4.182%   $76.3967   $76.40   $76.40   $76.40  
  Purchase #2 $188.80   9.190%   $206.1507   $206.15   $206.15   $206.20  
  Purchase #3 $94.38   4.662%   $98.78   $98.78   $98.80   $98.80  
  Purchase #4 $145.38   11.805%   $162.5421   $162.54   $162.55   $162.50  
  Purchase #5 $121.66   6.224%   $129.2321   $129.23   $129.25   $129.20  
  Purchase #6 $151.58   6.625%   $161.6222   $161.62   $161.60   $161.60  
  Purchase #7 $226.79   6.485%   $241.4973   $241.50   $241.50   $241.50  
  7 purchase totals = $1,001.92       $1,076.2211   $1,076.22   $1,076.25   $1,076.20