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 $118.94   5.466%   $125.4413   $125.44   $125.45   $125.40  
  Purchase #2 $29.84   7.419%   $32.0538   $32.05   $32.05   $32.10  
  Purchase #3 $189.61   6.445%   $201.8304   $201.83   $201.85   $201.80  
  Purchase #4 $165.67   6.320%   $176.1403   $176.14   $176.15   $176.10  
  Purchase #5 $110.57   5.710%   $116.8835   $116.88   $116.90   $116.90  
  Purchase #6 $221.76   6.761%   $236.7532   $236.75   $236.75   $236.80  
  Purchase #7 $217.33   3.550%   $225.0452   $225.05   $225.05   $225.00  
  7 purchase totals = $1,053.72       $1,114.1477   $1,114.14   $1,114.20   $1,114.10