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 $193.65   6.357%   $205.9603   $205.96   $205.95   $206.00  
  Purchase #2 $200.93   7.234%   $215.4653   $215.47   $215.45   $215.50  
  Purchase #3 $173.59   10.325%   $191.5132   $191.51   $191.50   $191.50  
  Purchase #4 $5.49   5.281%   $5.7799   $5.78   $5.80   $5.80  
  Purchase #5 $229.35   3.551%   $237.4942   $237.49   $237.50   $237.50  
  Purchase #6 $228.35   11.586%   $254.8066   $254.81   $254.80   $254.80  
  Purchase #7 $174.35   5.686%   $184.2635   $184.26   $184.25   $184.30  
  7 purchase totals = $1,205.71       $1,295.2830   $1,295.28   $1,295.25   $1,295.40