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 $89.69   6.130%   $95.188   $95.19   $95.20   $95.20  
  Purchase #2 $228.30   9.410%   $249.783   $249.78   $249.80   $249.80  
  Purchase #3 $114.58   7.384%   $123.0406   $123.04   $123.05   $123.00  
  Purchase #4 $153.90   12.872%   $173.71   $173.71   $173.70   $173.70  
  Purchase #5 $129.42   12.438%   $145.5173   $145.52   $145.50   $145.50  
  Purchase #6 $187.95   8.320%   $203.5874   $203.59   $203.60   $203.60  
  Purchase #7 $167.75   6.206%   $178.1606   $178.16   $178.15   $178.20  
  7 purchase totals = $1,071.59       $1,168.9869   $1,168.99   $1,169.00   $1,169.00