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 $212.64   13.481%   $241.306   $241.31   $241.30   $241.30  
  Purchase #2 $181.51   3.326%   $187.547   $187.55   $187.55   $187.50  
  Purchase #3 $62.34   8.480%   $67.6264   $67.63   $67.65   $67.60  
  Purchase #4 $225.60   6.428%   $240.1016   $240.10   $240.10   $240.10  
  Purchase #5 $148.93   5.614%   $157.2909   $157.29   $157.30   $157.30  
  Purchase #6 $94.41   12.784%   $106.4794   $106.48   $106.50   $106.50  
  Purchase #7 $101.36   12.745%   $114.2783   $114.28   $114.30   $114.30  
  7 purchase totals = $1,026.79       $1,114.6296   $1,114.64   $1,114.70   $1,114.60