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 $88.56   7.225%   $94.9585   $94.96   $94.95   $95.00  
  Purchase #2 $177.49   4.766%   $185.9492   $185.95   $185.95   $185.90  
  Purchase #3 $61.74   7.723%   $66.5082   $66.51   $66.50   $66.50  
  Purchase #4 $128.39   4.446%   $134.0982   $134.10   $134.10   $134.10  
  Purchase #5 $140.72   3.555%   $145.7226   $145.72   $145.70   $145.70  
  Purchase #6 $248.47   12.577%   $279.7201   $279.72   $279.70   $279.70  
  Purchase #7 $226.97   7.540%   $244.0835   $244.08   $244.10   $244.10  
  7 purchase totals = $1,072.34       $1,151.0403   $1,151.04   $1,151.00   $1,151.00