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 $88.98   7.525%   $95.6757   $95.68   $95.70   $95.70  
  Purchase #2 $192.96   7.777%   $207.9665   $207.97   $207.95   $208.00  
  Purchase #3 $175.56   4.831%   $184.0413   $184.04   $184.05   $184.00  
  Purchase #4 $138.49   9.750%   $151.9928   $151.99   $152.00   $152.00  
  Purchase #5 $157.68   13.209%   $178.508   $178.51   $178.50   $178.50  
  Purchase #6 $220.50   11.494%   $245.8443   $245.84   $245.85   $245.80  
  Purchase #7 $96.33   5.156%   $101.2968   $101.30   $101.30   $101.30  
  7 purchase totals = $1,070.50       $1,165.3254   $1,165.33   $1,165.35   $1,165.30