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	$185.94	5.187%	$195.5847	$195.58	$195.60	$195.60
Purchase #2	$38.28	5.676%	$40.4528	$40.45	$40.45	$40.50
Purchase #3	$113.44	10.141%	$124.944	$124.94	$124.95	$124.90
Purchase #4	$245.93	9.161%	$268.4596	$268.46	$268.45	$268.50
Purchase #5	$124.99	10.308%	$137.874	$137.87	$137.85	$137.90
Purchase #6	$192.69	8.427%	$208.928	$208.93	$208.95	$208.90
Purchase #7	$196.29	6.436%	$208.9232	$208.92	$208.90	$208.90
7 purchase totals =	$1,097.56		$1,185.1663	$1,185.15	$1,185.15	$1,185.20