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 $88.26   8.680%   $95.921   $95.92   $95.90   $95.90  
  Purchase #2 $245.69   5.457%   $259.0973   $259.10   $259.10   $259.10  
  Purchase #3 $149.44   3.850%   $155.1934   $155.19   $155.20   $155.20  
  Purchase #4 $49.89   8.425%   $54.0932   $54.09   $54.10   $54.10  
  Purchase #5 $120.52   4.637%   $126.1085   $126.11   $126.10   $126.10  
  Purchase #6 $41.59   6.401%   $44.2522   $44.25   $44.25   $44.30  
  Purchase #7 $190.87   3.838%   $198.1956   $198.20   $198.20   $198.20  
  7 purchase totals = $886.26       $932.8612   $932.86   $932.85   $932.90