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 $167.95   8.493%   $182.214   $182.21   $182.20   $182.20  
  Purchase #2 $216.44   8.350%   $234.5127   $234.51   $234.50   $234.50  
  Purchase #3 $43.67   4.470%   $45.622   $45.62   $45.60   $45.60  
  Purchase #4 $234.68   13.543%   $266.4627   $266.46   $266.45   $266.50  
  Purchase #5 $148.35   8.234%   $160.5651   $160.57   $160.55   $160.60  
  Purchase #6 $12.61   3.570%   $13.0602   $13.06   $13.05   $13.10  
  Purchase #7 $247.35   4.404%   $258.2433   $258.24   $258.25   $258.20  
  7 purchase totals = $1,071.05       $1,160.6800   $1,160.67   $1,160.60   $1,160.70