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 $114.60   9.690%   $125.7047   $125.70   $125.70   $125.70  
  Purchase #2 $68.81   12.627%   $77.4986   $77.50   $77.50   $77.50  
  Purchase #3 $137.55   11.741%   $153.6997   $153.70   $153.70   $153.70  
  Purchase #4 $203.72   13.170%   $230.5499   $230.55   $230.55   $230.50  
  Purchase #5 $152.99   10.580%   $169.1763   $169.18   $169.20   $169.20  
  Purchase #6 $188.57   5.367%   $198.6906   $198.69   $198.70   $198.70  
  Purchase #7 $202.52   4.531%   $211.6962   $211.70   $211.70   $211.70  
  7 purchase totals = $1,068.76       $1,167.0160   $1,167.02   $1,167.05   $1,167.00