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 $87.34   8.813%   $95.0373   $95.04   $95.05   $95.00  
  Purchase #2 $173.33   5.170%   $182.2912   $182.29   $182.30   $182.30  
  Purchase #3 $52.25   7.825%   $56.3386   $56.34   $56.35   $56.30  
  Purchase #4 $49.46   9.370%   $54.0944   $54.09   $54.10   $54.10  
  Purchase #5 $205.91   9.492%   $225.455   $225.46   $225.45   $225.50  
  Purchase #6 $233.89   11.505%   $260.799   $260.80   $260.80   $260.80  
  Purchase #7 $200.63   13.334%   $227.382   $227.38   $227.40   $227.40  
  7 purchase totals = $1,002.81       $1,101.3975   $1,101.40   $1,101.45   $1,101.40