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 $145.30   4.768%   $152.2279   $152.23   $152.25   $152.20  
  Purchase #2 $205.48   4.119%   $213.9437   $213.94   $213.95   $213.90  
  Purchase #3 $93.96   6.133%   $99.7226   $99.72   $99.70   $99.70  
  Purchase #4 $218.80   6.763%   $233.5974   $233.60   $233.60   $233.60  
  Purchase #5 $88.71   6.521%   $94.4948   $94.49   $94.50   $94.50  
  Purchase #6 $148.93   8.480%   $161.5593   $161.56   $161.55   $161.60  
  Purchase #7 $85.69   3.244%   $88.4698   $88.47   $88.45   $88.50  
  7 purchase totals = $986.87       $1,044.0155   $1,044.01   $1,044.00   $1,044.00