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 $219.95   3.509%   $227.668   $227.67   $227.65   $227.70  
  Purchase #2 $223.47   12.762%   $251.9892   $251.99   $252.00   $252.00  
  Purchase #3 $90.62   6.754%   $96.7405   $96.74   $96.75   $96.70  
  Purchase #4 $227.42   7.418%   $244.29   $244.29   $244.30   $244.30  
  Purchase #5 $200.77   11.326%   $223.5092   $223.51   $223.50   $223.50  
  Purchase #6 $39.31   4.618%   $41.1253   $41.13   $41.15   $41.10  
  Purchase #7 $8.82   10.121%   $9.7127   $9.71   $9.70   $9.70  
  7 purchase totals = $1,010.36       $1,095.0349   $1,095.04   $1,095.05   $1,095.00