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 $196.50   4.512%   $205.3661   $205.37   $205.35   $205.40  
  Purchase #2 $213.53   5.528%   $225.3339   $225.33   $225.35   $225.30  
  Purchase #3 $64.79   6.424%   $68.9521   $68.95   $68.95   $69.00  
  Purchase #4 $151.70   5.484%   $160.0192   $160.02   $160.00   $160.00  
  Purchase #5 $185.30   5.197%   $194.93   $194.93   $194.95   $194.90  
  Purchase #6 $194.44   7.302%   $208.638   $208.64   $208.65   $208.60  
  Purchase #7 $169.63   5.144%   $178.3558   $178.36   $178.35   $178.40  
  7 purchase totals = $1,175.89       $1,241.5951   $1,241.60   $1,241.60   $1,241.60