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 $58.68   5.645%   $61.9925   $61.99   $62.00   $62.00  
  Purchase #2 $135.43   8.822%   $147.3776   $147.38   $147.40   $147.40  
  Purchase #3 $40.69   13.466%   $46.1693   $46.17   $46.15   $46.20  
  Purchase #4 $232.88   9.345%   $254.6426   $254.64   $254.65   $254.60  
  Purchase #5 $227.67   5.684%   $240.6108   $240.61   $240.60   $240.60  
  Purchase #6 $202.50   11.497%   $225.7814   $225.78   $225.80   $225.80  
  Purchase #7 $120.96   3.128%   $124.7436   $124.74   $124.75   $124.70  
  7 purchase totals = $1,018.81       $1,101.3178   $1,101.31   $1,101.35   $1,101.30