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 $184.81   5.857%   $195.6343   $195.63   $195.65   $195.60  
  Purchase #2 $24.63   11.861%   $27.5514   $27.55   $27.55   $27.60  
  Purchase #3 $232.44   5.299%   $244.757   $244.76   $244.75   $244.80  
  Purchase #4 $206.98   13.184%   $234.2682   $234.27   $234.25   $234.30  
  Purchase #5 $159.53   12.544%   $179.5414   $179.54   $179.55   $179.50  
  Purchase #6 $95.43   11.254%   $106.1697   $106.17   $106.15   $106.20  
  Purchase #7 $160.77   6.648%   $171.458   $171.46   $171.45   $171.50  
  7 purchase totals = $1,064.59       $1,159.3800   $1,159.38   $1,159.35   $1,159.50