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 $88.52   7.354%   $95.0298   $95.03   $95.05   $95.00  
  Purchase #2 $222.77   10.785%   $246.7957   $246.80   $246.80   $246.80  
  Purchase #3 $247.99   7.417%   $266.3834   $266.38   $266.40   $266.40  
  Purchase #4 $44.76   5.384%   $47.1699   $47.17   $47.15   $47.20  
  Purchase #5 $82.30   11.385%   $91.6699   $91.67   $91.65   $91.70  
  Purchase #6 $172.42   5.442%   $181.8031   $181.80   $181.80   $181.80  
  Purchase #7 $191.54   3.250%   $197.7651   $197.77   $197.75   $197.80  
  7 purchase totals = $1,050.30       $1,126.6169   $1,126.62   $1,126.60   $1,126.70