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 $96.56   9.760%   $105.9843   $105.98   $106.00   $106.00  
  Purchase #2 $238.48   10.512%   $263.549   $263.55   $263.55   $263.50  
  Purchase #3 $126.71   4.626%   $132.5716   $132.57   $132.55   $132.60  
  Purchase #4 $191.65   7.340%   $205.7171   $205.72   $205.70   $205.70  
  Purchase #5 $202.31   4.163%   $210.7322   $210.73   $210.75   $210.70  
  Purchase #6 $47.79   10.115%   $52.624   $52.62   $52.60   $52.60  
  Purchase #7 $198.25   3.104%   $204.4037   $204.40   $204.40   $204.40  
  7 purchase totals = $1,101.75       $1,175.5819   $1,175.57   $1,175.55   $1,175.50