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 $61.53   3.187%   $63.491   $63.49   $63.50   $63.50  
  Purchase #2 $206.53   4.426%   $215.671   $215.67   $215.65   $215.70  
  Purchase #3 $76.35   10.707%   $84.5248   $84.52   $84.50   $84.50  
  Purchase #4 $107.77   4.266%   $112.3675   $112.37   $112.35   $112.40  
  Purchase #5 $222.56   3.631%   $230.6412   $230.64   $230.65   $230.60  
  Purchase #6 $160.58   7.386%   $172.4404   $172.44   $172.45   $172.40  
  Purchase #7 $177.95   7.698%   $191.6486   $191.65   $191.65   $191.60  
  7 purchase totals = $1,013.27       $1,070.7845   $1,070.78   $1,070.75   $1,070.70