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 $41.75   5.267%   $43.949   $43.95   $43.95   $43.90  
  Purchase #2 $67.41   12.293%   $75.6967   $75.70   $75.70   $75.70  
  Purchase #3 $120.95   8.202%   $130.8703   $130.87   $130.85   $130.90  
  Purchase #4 $243.66   4.203%   $253.901   $253.90   $253.90   $253.90  
  Purchase #5 $13.56   6.658%   $14.4628   $14.46   $14.45   $14.50  
  Purchase #6 $201.83   6.629%   $215.2093   $215.21   $215.20   $215.20  
  Purchase #7 $185.68   6.728%   $198.1726   $198.17   $198.15   $198.20  
  7 purchase totals = $874.84       $932.2617   $932.26   $932.20   $932.30