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 $211.80   7.534%   $227.757   $227.76   $227.75   $227.80  
  Purchase #2 $67.28   13.140%   $76.1206   $76.12   $76.10   $76.10  
  Purchase #3 $13.33   8.529%   $14.4669   $14.47   $14.45   $14.50  
  Purchase #4 $78.59   3.185%   $81.0931   $81.09   $81.10   $81.10  
  Purchase #5 $153.32   6.402%   $163.1355   $163.14   $163.15   $163.10  
  Purchase #6 $231.86   9.815%   $254.6171   $254.62   $254.60   $254.60  
  Purchase #7 $220.28   10.503%   $243.416   $243.42   $243.40   $243.40  
  7 purchase totals = $976.46       $1,060.6062   $1,060.62   $1,060.55   $1,060.60