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 $83.44   13.806%   $94.9597   $94.96   $94.95   $95.00  
  Purchase #2 $214.28   8.148%   $231.7395   $231.74   $231.75   $231.70  
  Purchase #3 $53.54   5.361%   $56.4103   $56.41   $56.40   $56.40  
  Purchase #4 $232.75   6.565%   $248.03   $248.03   $248.05   $248.00  
  Purchase #5 $221.78   9.279%   $242.359   $242.36   $242.35   $242.40  
  Purchase #6 $139.26   13.183%   $157.6186   $157.62   $157.60   $157.60  
  Purchase #7 $63.65   12.829%   $71.8157   $71.82   $71.80   $71.80  
  7 purchase totals = $1,008.70       $1,102.9328   $1,102.94   $1,102.90   $1,102.90