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 $91.95   3.373%   $95.0515   $95.05   $95.05   $95.10  
  Purchase #2 $54.25   4.852%   $56.8822   $56.88   $56.90   $56.90  
  Purchase #3 $44.31   7.453%   $47.6124   $47.61   $47.60   $47.60  
  Purchase #4 $77.61   13.164%   $87.8266   $87.83   $87.85   $87.80  
  Purchase #5 $191.29   5.748%   $202.2853   $202.29   $202.30   $202.30  
  Purchase #6 $196.86   11.698%   $219.8887   $219.89   $219.90   $219.90  
  Purchase #7 $133.92   13.698%   $152.2644   $152.26   $152.25   $152.30  
  7 purchase totals = $790.19       $861.8111   $861.81   $861.85   $861.90