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 $88.35   7.482%   $94.9603   $94.96   $94.95   $95.00  
  Purchase #2 $232.70   3.225%   $240.2046   $240.20   $240.20   $240.20  
  Purchase #3 $19.59   10.336%   $21.6148   $21.61   $21.60   $21.60  
  Purchase #4 $99.88   8.646%   $108.5156   $108.52   $108.50   $108.50  
  Purchase #5 $124.28   4.399%   $129.7471   $129.75   $129.75   $129.70  
  Purchase #6 $250.50   7.645%   $269.6507   $269.65   $269.65   $269.70  
  Purchase #7 $209.56   9.184%   $228.806   $228.81   $228.80   $228.80  
  7 purchase totals = $1,024.86       $1,093.4991   $1,093.50   $1,093.45   $1,093.50