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 $87.54   8.577%   $95.0483   $95.05   $95.05   $95.00  
  Purchase #2 $238.90   10.296%   $263.4971   $263.50   $263.50   $263.50  
  Purchase #3 $207.39   10.842%   $229.8752   $229.88   $229.90   $229.90  
  Purchase #4 $181.29   3.218%   $187.1239   $187.12   $187.10   $187.10  
  Purchase #5 $163.70   5.183%   $172.1846   $172.18   $172.20   $172.20  
  Purchase #6 $42.28   4.499%   $44.1822   $44.18   $44.20   $44.20  
  Purchase #7 $73.44   7.402%   $78.876   $78.88   $78.90   $78.90  
  7 purchase totals = $994.54       $1,070.7873   $1,070.79   $1,070.85   $1,070.80