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 $98.62   7.433%   $105.9504   $105.95   $105.95   $106.00  
  Purchase #2 $11.31   3.789%   $11.7385   $11.74   $11.75   $11.70  
  Purchase #3 $68.88   6.569%   $73.4047   $73.40   $73.40   $73.40  
  Purchase #4 $147.94   9.750%   $162.3642   $162.36   $162.35   $162.40  
  Purchase #5 $199.32   6.458%   $212.1921   $212.19   $212.20   $212.20  
  Purchase #6 $187.41   7.350%   $201.1846   $201.18   $201.20   $201.20  
  Purchase #7 $167.51   9.789%   $183.9076   $183.91   $183.90   $183.90  
  7 purchase totals = $880.99       $950.7421   $950.73   $950.75   $950.80