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 $162.49   8.338%   $176.0384   $176.04   $176.05   $176.00  
  Purchase #2 $175.64   12.503%   $197.6003   $197.60   $197.60   $197.60  
  Purchase #3 $30.70   8.156%   $33.2039   $33.20   $33.20   $33.20  
  Purchase #4 $99.62   13.408%   $112.977   $112.98   $113.00   $113.00  
  Purchase #5 $157.57   6.634%   $168.0232   $168.02   $168.00   $168.00  
  Purchase #6 $185.71   13.812%   $211.3603   $211.36   $211.35   $211.40  
  Purchase #7 $51.49   8.707%   $55.9732   $55.97   $55.95   $56.00  
  7 purchase totals = $863.22       $955.1763   $955.17   $955.15   $955.20