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 $92.44   3.651%   $95.815   $95.82   $95.80   $95.80  
  Purchase #2 $218.29   12.327%   $245.1986   $245.20   $245.20   $245.20  
  Purchase #3 $188.31   7.325%   $202.1037   $202.10   $202.10   $202.10  
  Purchase #4 $20.95   7.102%   $22.4379   $22.44   $22.45   $22.40  
  Purchase #5 $144.54   5.296%   $152.1948   $152.19   $152.20   $152.20  
  Purchase #6 $242.51   7.386%   $260.4218   $260.42   $260.40   $260.40  
  Purchase #7 $6.41   12.564%   $7.2154   $7.22   $7.20   $7.20  
  7 purchase totals = $913.45       $985.3872   $985.39   $985.35   $985.30