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 $86.86   9.369%   $94.9979   $95.00   $95.00   $95.00  
  Purchase #2 $54.32   5.763%   $57.4505   $57.45   $57.45   $57.50  
  Purchase #3 $169.49   10.816%   $187.822   $187.82   $187.80   $187.80  
  Purchase #4 $235.25   12.413%   $264.4516   $264.45   $264.45   $264.50  
  Purchase #5 $226.34   4.447%   $236.4053   $236.41   $236.40   $236.40  
  Purchase #6 $25.82   13.470%   $29.298   $29.30   $29.30   $29.30  
  Purchase #7 $101.51   12.663%   $114.3642   $114.36   $114.35   $114.40  
  7 purchase totals = $899.59       $984.7895   $984.79   $984.75   $984.90