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 $119.28   5.379%   $125.6961   $125.70   $125.70   $125.70  
  Purchase #2 $203.92   6.573%   $217.3237   $217.32   $217.30   $217.30  
  Purchase #3 $78.29   3.753%   $81.2282   $81.23   $81.25   $81.20  
  Purchase #4 $112.69   5.701%   $119.1145   $119.11   $119.10   $119.10  
  Purchase #5 $244.95   7.419%   $263.1228   $263.12   $263.10   $263.10  
  Purchase #6 $166.79   4.785%   $174.7709   $174.77   $174.75   $174.80  
  Purchase #7 $191.45   5.681%   $202.3263   $202.33   $202.35   $202.30  
  7 purchase totals = $1,117.37       $1,183.5825   $1,183.58   $1,183.55   $1,183.50