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 $59.64   5.772%   $63.0824   $63.08   $63.10   $63.10  
  Purchase #2 $208.91   7.868%   $225.347   $225.35   $225.35   $225.30  
  Purchase #3 $206.37   3.861%   $214.3379   $214.34   $214.35   $214.30  
  Purchase #4 $36.85   7.498%   $39.613   $39.61   $39.60   $39.60  
  Purchase #5 $191.51   7.189%   $205.2777   $205.28   $205.30   $205.30  
  Purchase #6 $210.42   6.248%   $223.567   $223.57   $223.55   $223.60  
  Purchase #7 $117.56   5.167%   $123.6343   $123.63   $123.65   $123.60  
  7 purchase totals = $1,031.26       $1,094.8593   $1,094.86   $1,094.90   $1,094.80