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 $85.84   11.859%   $96.0198   $96.02   $96.00   $96.00  
  Purchase #2 $225.86   7.792%   $243.459   $243.46   $243.45   $243.50  
  Purchase #3 $70.80   9.274%   $77.366   $77.37   $77.35   $77.40  
  Purchase #4 $162.66   9.594%   $178.2656   $178.27   $178.25   $178.30  
  Purchase #5 $189.34   9.370%   $207.0812   $207.08   $207.10   $207.10  
  Purchase #6 $218.41   6.853%   $233.3776   $233.38   $233.40   $233.40  
  Purchase #7 $192.74   6.532%   $205.3298   $205.33   $205.35   $205.30  
  7 purchase totals = $1,145.65       $1,240.8990   $1,240.91   $1,240.90   $1,241.00