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 $60.93   3.498%   $63.0613   $63.06   $63.05   $63.10  
  Purchase #2 $210.71   4.110%   $219.3702   $219.37   $219.35   $219.40  
  Purchase #3 $249.55   4.237%   $260.1234   $260.12   $260.10   $260.10  
  Purchase #4 $79.90   6.167%   $84.8274   $84.83   $84.85   $84.80  
  Purchase #5 $201.32   12.690%   $226.8675   $226.87   $226.85   $226.90  
  Purchase #6 $191.50   9.726%   $210.1253   $210.13   $210.15   $210.10  
  Purchase #7 $82.54   6.108%   $87.5815   $87.58   $87.60   $87.60  
  7 purchase totals = $1,076.45       $1,151.9566   $1,151.96   $1,151.95   $1,152.00