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 $69.44   6.570%   $74.0022   $74.00   $74.00   $74.00  
  Purchase #2 $216.96   9.441%   $237.4432   $237.44   $237.45   $237.40  
  Purchase #3 $218.67   10.544%   $241.7266   $241.73   $241.75   $241.70  
  Purchase #4 $63.99   8.265%   $69.2788   $69.28   $69.30   $69.30  
  Purchase #5 $192.74   5.330%   $203.013   $203.01   $203.00   $203.00  
  Purchase #6 $190.29   3.344%   $196.6533   $196.65   $196.65   $196.70  
  Purchase #7 $64.86   9.610%   $71.093   $71.09   $71.10   $71.10  
  7 purchase totals = $1,016.95       $1,093.2101   $1,093.20   $1,093.25   $1,093.20