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 $131.52   4.561%   $137.5186   $137.52   $137.50   $137.50  
  Purchase #2 $194.27   10.157%   $214.002   $214.00   $214.00   $214.00  
  Purchase #3 $222.54   10.404%   $245.6931   $245.69   $245.70   $245.70  
  Purchase #4 $201.60   5.833%   $213.3593   $213.36   $213.35   $213.40  
  Purchase #5 $187.58   11.828%   $209.767   $209.77   $209.75   $209.80  
  Purchase #6 $200.62   10.508%   $221.7011   $221.70   $221.70   $221.70  
  Purchase #7 $238.28   6.302%   $253.2964   $253.30   $253.30   $253.30  
  7 purchase totals = $1,376.41       $1,495.3375   $1,495.34   $1,495.30   $1,495.40