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 $160.51   8.824%   $174.6734   $174.67   $174.65   $174.70  
  Purchase #2 $163.90   8.658%   $178.0905   $178.09   $178.10   $178.10  
  Purchase #3 $250.88   5.818%   $265.4762   $265.48   $265.50   $265.50  
  Purchase #4 $42.26   9.770%   $46.3888   $46.39   $46.40   $46.40  
  Purchase #5 $200.98   5.624%   $212.2831   $212.28   $212.30   $212.30  
  Purchase #6 $135.55   8.807%   $147.4879   $147.49   $147.50   $147.50  
  Purchase #7 $67.35   5.478%   $71.0394   $71.04   $71.05   $71.00  
  7 purchase totals = $1,021.43       $1,095.4393   $1,095.44   $1,095.50   $1,095.50