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 $195.31   3.212%   $201.5834   $201.58   $201.60   $201.60  
  Purchase #2 $206.92   12.795%   $233.3954   $233.40   $233.40   $233.40  
  Purchase #3 $167.35   3.668%   $173.4884   $173.49   $173.50   $173.50  
  Purchase #4 $179.42   7.788%   $193.3932   $193.39   $193.40   $193.40  
  Purchase #5 $90.58   4.727%   $94.8617   $94.86   $94.85   $94.90  
  Purchase #6 $191.98   11.373%   $213.8139   $213.81   $213.80   $213.80  
  Purchase #7 $228.27   3.315%   $235.8372   $235.84   $235.85   $235.80  
  7 purchase totals = $1,259.83       $1,346.3732   $1,346.37   $1,346.40   $1,346.40