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 $44.42   5.654%   $46.9315   $46.93   $46.95   $46.90  
  Purchase #2 $247.54   10.525%   $273.5936   $273.59   $273.60   $273.60  
  Purchase #3 $13.46   10.705%   $14.9009   $14.90   $14.90   $14.90  
  Purchase #4 $192.56   4.456%   $201.1405   $201.14   $201.15   $201.10  
  Purchase #5 $185.95   6.158%   $197.4008   $197.40   $197.40   $197.40  
  Purchase #6 $150.79   6.118%   $160.0153   $160.02   $160.00   $160.00  
  Purchase #7 $179.50   12.139%   $201.2895   $201.29   $201.30   $201.30  
  7 purchase totals = $1,014.22       $1,095.2721   $1,095.27   $1,095.30   $1,095.20