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 $59.42   5.572%   $62.7309   $62.73   $62.75   $62.70  
  Purchase #2 $246.62   5.530%   $260.2581   $260.26   $260.25   $260.30  
  Purchase #3 $19.31   5.467%   $20.3657   $20.37   $20.35   $20.40  
  Purchase #4 $235.30   9.495%   $257.6417   $257.64   $257.65   $257.60  
  Purchase #5 $248.28   9.608%   $272.1347   $272.13   $272.15   $272.10  
  Purchase #6 $60.93   4.809%   $63.8601   $63.86   $63.85   $63.90  
  Purchase #7 $16.68   6.476%   $17.7602   $17.76   $17.75   $17.80  
  7 purchase totals = $886.54       $954.7514   $954.75   $954.75   $954.80