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 $79.36   8.300%   $85.9469   $85.95   $85.95   $85.90  
  Purchase #2 $190.91   7.412%   $205.0602   $205.06   $205.05   $205.10  
  Purchase #3 $169.62   4.791%   $177.7465   $177.75   $177.75   $177.70  
  Purchase #4 $162.55   7.269%   $174.3658   $174.37   $174.35   $174.40  
  Purchase #5 $90.90   5.634%   $96.0213   $96.02   $96.00   $96.00  
  Purchase #6 $249.75   5.423%   $263.2939   $263.29   $263.30   $263.30  
  Purchase #7 $232.52   12.167%   $260.8107   $260.81   $260.80   $260.80  
  7 purchase totals = $1,175.61       $1,263.2453   $1,263.25   $1,263.20   $1,263.20