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 $108.51   9.679%   $119.0127   $119.01   $119.00   $119.00  
  Purchase #2 $199.81   13.165%   $226.115   $226.12   $226.10   $226.10  
  Purchase #3 $87.57   4.184%   $91.2339   $91.23   $91.25   $91.20  
  Purchase #4 $241.64   10.368%   $266.6932   $266.69   $266.70   $266.70  
  Purchase #5 $74.88   3.307%   $77.3563   $77.36   $77.35   $77.40  
  Purchase #6 $83.64   3.753%   $86.779   $86.78   $86.80   $86.80  
  Purchase #7 $218.28   7.328%   $234.2756   $234.28   $234.30   $234.30  
  7 purchase totals = $1,014.33       $1,101.4657   $1,101.47   $1,101.50   $1,101.50