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 $180.80   8.270%   $195.7522   $195.75   $195.75   $195.80  
  Purchase #2 $155.68   8.556%   $169   $169.00   $169.00   $169.00  
  Purchase #3 $43.49   6.399%   $46.2729   $46.27   $46.25   $46.30  
  Purchase #4 $168.54   9.575%   $184.6777   $184.68   $184.70   $184.70  
  Purchase #5 $93.56   4.609%   $97.8722   $97.87   $97.85   $97.90  
  Purchase #6 $186.73   11.299%   $207.8286   $207.83   $207.85   $207.80  
  Purchase #7 $127.53   6.424%   $135.7225   $135.72   $135.70   $135.70  
  7 purchase totals = $956.33       $1,037.1261   $1,037.12   $1,037.10   $1,037.20