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 $167.96   5.233%   $176.7493   $176.75   $176.75   $176.70  
  Purchase #2 $175.85   11.512%   $196.0939   $196.09   $196.10   $196.10  
  Purchase #3 $177.92   6.626%   $189.709   $189.71   $189.70   $189.70  
  Purchase #4 $246.78   8.179%   $266.9641   $266.96   $266.95   $267.00  
  Purchase #5 $167.45   4.685%   $175.295   $175.30   $175.30   $175.30  
  Purchase #6 $156.69   7.176%   $167.9341   $167.93   $167.95   $167.90  
  Purchase #7 $174.94   8.361%   $189.5667   $189.57   $189.55   $189.60  
  7 purchase totals = $1,267.59       $1,362.3121   $1,362.31   $1,362.30   $1,362.30