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 $212.86   6.314%   $226.3   $226.30   $226.30   $226.30  
  Purchase #2 $224.25   6.379%   $238.5549   $238.55   $238.55   $238.60  
  Purchase #3 $43.25   6.547%   $46.0816   $46.08   $46.10   $46.10  
  Purchase #4 $62.58   3.309%   $64.6508   $64.65   $64.65   $64.70  
  Purchase #5 $154.31   5.134%   $162.2323   $162.23   $162.25   $162.20  
  Purchase #6 $218.89   13.674%   $248.821   $248.82   $248.80   $248.80  
  Purchase #7 $141.84   4.116%   $147.6781   $147.68   $147.70   $147.70  
  7 purchase totals = $1,057.98       $1,134.3187   $1,134.31   $1,134.35   $1,134.40