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	$80.61	5.280%	$84.8662	$84.87	$84.85	$84.90
Purchase #2	$7.29	7.839%	$7.8615	$7.86	$7.85	$7.90
Purchase #3	$24.66	3.681%	$25.5677	$25.57	$25.55	$25.60
Purchase #4	$98.43	11.678%	$109.9247	$109.92	$109.90	$109.90
Purchase #5	$130.50	9.871%	$143.3817	$143.38	$143.40	$143.40
Purchase #6	$150.99	3.542%	$156.3381	$156.34	$156.35	$156.30
Purchase #7	$171.41	8.819%	$186.5266	$186.53	$186.55	$186.50
7 purchase totals =	$663.89		$714.4665	$714.47	$714.45	$714.50