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 $194.71   8.457%   $211.1766   $211.18   $211.20   $211.20  
  Purchase #2 $250.92   12.290%   $281.7581   $281.76   $281.75   $281.80  
  Purchase #3 $24.84   5.260%   $26.1466   $26.15   $26.15   $26.10  
  Purchase #4 $69.51   11.729%   $77.6628   $77.66   $77.65   $77.70  
  Purchase #5 $75.58   3.465%   $78.1988   $78.20   $78.20   $78.20  
  Purchase #6 $170.54   7.334%   $183.0474   $183.05   $183.05   $183.00  
  Purchase #7 $228.70   3.629%   $236.9995   $237.00   $237.00   $237.00  
  7 purchase totals = $1,014.80       $1,094.9898   $1,095.00   $1,095.00   $1,095.00