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 $195.97   7.532%   $210.7305   $210.73   $210.75   $210.70  
  Purchase #2 $196.28   4.294%   $204.7083   $204.71   $204.70   $204.70  
  Purchase #3 $194.83   12.761%   $219.6923   $219.69   $219.70   $219.70  
  Purchase #4 $223.28   9.427%   $244.3286   $244.33   $244.35   $244.30  
  Purchase #5 $172.88   11.366%   $192.5295   $192.53   $192.55   $192.50  
  Purchase #6 $188.68   3.535%   $195.3498   $195.35   $195.35   $195.30  
  Purchase #7 $93.33   9.419%   $102.1208   $102.12   $102.10   $102.10  
  7 purchase totals = $1,265.25       $1,369.4598   $1,369.46   $1,369.50   $1,369.30