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 $85.75   9.600%   $93.982   $93.98   $94.00   $94.00  
  Purchase #2 $234.32   12.701%   $264.081   $264.08   $264.10   $264.10  
  Purchase #3 $178.38   3.472%   $184.5734   $184.57   $184.55   $184.60  
  Purchase #4 $236.58   10.463%   $261.3334   $261.33   $261.35   $261.30  
  Purchase #5 $12.83   9.572%   $14.0581   $14.06   $14.05   $14.10  
  Purchase #6 $139.76   8.119%   $151.1071   $151.11   $151.10   $151.10  
  Purchase #7 $165.63   11.306%   $184.3561   $184.36   $184.35   $184.40  
  7 purchase totals = $1,053.25       $1,153.4911   $1,153.49   $1,153.50   $1,153.60