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 $106.68   6.863%   $114.0014   $114.00   $114.00   $114.00  
  Purchase #2 $185.34   8.813%   $201.674   $201.67   $201.65   $201.70  
  Purchase #3 $32.60   11.626%   $36.3901   $36.39   $36.40   $36.40  
  Purchase #4 $174.67   10.211%   $192.5056   $192.51   $192.50   $192.50  
  Purchase #5 $188.97   13.304%   $214.1106   $214.11   $214.10   $214.10  
  Purchase #6 $80.49   3.352%   $83.188   $83.19   $83.20   $83.20  
  Purchase #7 $162.40   5.144%   $170.7539   $170.75   $170.75   $170.80  
  7 purchase totals = $931.15       $1,012.6236   $1,012.62   $1,012.60   $1,012.70