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 $162.25   6.581%   $172.9277   $172.93   $172.95   $172.90  
  Purchase #2 $37.38   3.573%   $38.7156   $38.72   $38.70   $38.70  
  Purchase #3 $167.73   11.469%   $186.967   $186.97   $186.95   $187.00  
  Purchase #4 $87.30   6.244%   $92.751   $92.75   $92.75   $92.80  
  Purchase #5 $203.34   3.676%   $210.8148   $210.81   $210.80   $210.80  
  Purchase #6 $196.56   10.157%   $216.5246   $216.52   $216.50   $216.50  
  Purchase #7 $168.37   11.452%   $187.6517   $187.65   $187.65   $187.70  
  7 purchase totals = $1,022.93       $1,106.3524   $1,106.35   $1,106.30   $1,106.40