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 $59.37   5.541%   $62.6597   $62.66   $62.65   $62.70  
  Purchase #2 $200.94   11.377%   $223.8009   $223.80   $223.80   $223.80  
  Purchase #3 $115.57   5.650%   $122.0997   $122.10   $122.10   $122.10  
  Purchase #4 $56.83   8.767%   $61.8123   $61.81   $61.80   $61.80  
  Purchase #5 $227.44   11.668%   $253.9777   $253.98   $254.00   $254.00  
  Purchase #6 $125.87   4.556%   $131.6046   $131.60   $131.60   $131.60  
  Purchase #7 $250.27   8.771%   $272.2212   $272.22   $272.20   $272.20  
  7 purchase totals = $1,036.29       $1,128.1761   $1,128.17   $1,128.15   $1,128.20