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 $86.25   9.741%   $94.6516   $94.65   $94.65   $94.70  
  Purchase #2 $165.54   9.445%   $181.1753   $181.18   $181.20   $181.20  
  Purchase #3 $232.80   5.812%   $246.3303   $246.33   $246.35   $246.30  
  Purchase #4 $215.31   3.110%   $222.0061   $222.01   $222.00   $222.00  
  Purchase #5 $73.35   13.367%   $83.1547   $83.15   $83.15   $83.20  
  Purchase #6 $176.88   12.594%   $199.1563   $199.16   $199.15   $199.20  
  Purchase #7 $166.71   5.407%   $175.724   $175.72   $175.70   $175.70  
  7 purchase totals = $1,116.84       $1,202.1983   $1,202.20   $1,202.20   $1,202.30