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 $88.30   7.623%   $95.0311   $95.03   $95.05   $95.00  
  Purchase #2 $225.41   4.256%   $235.0034   $235.00   $235.00   $235.00  
  Purchase #3 $236.81   5.583%   $250.0311   $250.03   $250.05   $250.00  
  Purchase #4 $197.41   8.735%   $214.6538   $214.65   $214.65   $214.70  
  Purchase #5 $180.34   4.870%   $189.1226   $189.12   $189.10   $189.10  
  Purchase #6 $165.91   8.543%   $180.0837   $180.08   $180.10   $180.10  
  Purchase #7 $156.83   3.807%   $162.8005   $162.80   $162.80   $162.80  
  7 purchase totals = $1,251.01       $1,326.7262   $1,326.71   $1,326.75   $1,326.70