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 $114.38   10.400%   $126.2755   $126.28   $126.30   $126.30  
  Purchase #2 $216.69   9.747%   $237.8108   $237.81   $237.80   $237.80  
  Purchase #3 $108.38   10.393%   $119.6439   $119.64   $119.65   $119.60  
  Purchase #4 $225.28   9.431%   $246.5262   $246.53   $246.55   $246.50  
  Purchase #5 $189.88   6.122%   $201.5045   $201.50   $201.50   $201.50  
  Purchase #6 $211.31   10.432%   $233.3539   $233.35   $233.35   $233.40  
  Purchase #7 $196.74   7.547%   $211.588   $211.59   $211.60   $211.60  
  7 purchase totals = $1,262.66       $1,376.7028   $1,376.70   $1,376.75   $1,376.70