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 $32.76   4.820%   $34.339   $34.34   $34.35   $34.30  
  Purchase #2 $230.72   8.688%   $250.765   $250.77   $250.75   $250.80  
  Purchase #3 $231.76   5.473%   $244.4442   $244.44   $244.45   $244.40  
  Purchase #4 $45.36   6.398%   $48.2621   $48.26   $48.25   $48.30  
  Purchase #5 $92.71   12.556%   $104.3507   $104.35   $104.35   $104.40  
  Purchase #6 $198.26   10.108%   $218.3001   $218.30   $218.30   $218.30  
  Purchase #7 $184.32   12.819%   $207.948   $207.95   $207.95   $207.90  
  7 purchase totals = $1,015.89       $1,108.4091   $1,108.41   $1,108.40   $1,108.40