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 $91.66   4.701%   $95.9689   $95.97   $95.95   $96.00  
  Purchase #2 $179.72   7.688%   $193.5369   $193.54   $193.55   $193.50  
  Purchase #3 $233.58   3.357%   $241.4213   $241.42   $241.40   $241.40  
  Purchase #4 $205.40   4.425%   $214.489   $214.49   $214.50   $214.50  
  Purchase #5 $86.79   10.537%   $95.9351   $95.94   $95.95   $95.90  
  Purchase #6 $157.30   6.460%   $167.4616   $167.46   $167.45   $167.50  
  Purchase #7 $90.94   3.178%   $93.8301   $93.83   $93.85   $93.80  
  7 purchase totals = $1,045.39       $1,102.6429   $1,102.65   $1,102.65   $1,102.60