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 $181.26   9.118%   $197.7873   $197.79   $197.80   $197.80  
  Purchase #2 $114.56   4.129%   $119.2902   $119.29   $119.30   $119.30  
  Purchase #3 $7.44   6.680%   $7.937   $7.94   $7.95   $7.90  
  Purchase #4 $147.78   3.679%   $153.2168   $153.22   $153.20   $153.20  
  Purchase #5 $235.58   3.239%   $243.2104   $243.21   $243.20   $243.20  
  Purchase #6 $237.82   3.499%   $246.1413   $246.14   $246.15   $246.10  
  Purchase #7 $187.58   7.455%   $201.5641   $201.56   $201.55   $201.60  
  7 purchase totals = $1,112.02       $1,169.1471   $1,169.15   $1,169.15   $1,169.10