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 $69.25   11.121%   $76.9513   $76.95   $76.95   $77.00  
  Purchase #2 $179.33   12.319%   $201.4217   $201.42   $201.40   $201.40  
  Purchase #3 $196.88   6.745%   $210.1596   $210.16   $210.15   $210.20  
  Purchase #4 $118.62   12.666%   $133.6444   $133.64   $133.65   $133.60  
  Purchase #5 $234.65   13.628%   $266.6281   $266.63   $266.65   $266.60  
  Purchase #6 $240.72   8.220%   $260.5072   $260.51   $260.50   $260.50  
  Purchase #7 $87.42   9.533%   $95.7537   $95.75   $95.75   $95.80  
  7 purchase totals = $1,126.87       $1,245.0660   $1,245.06   $1,245.05   $1,245.10