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	$194.31	12.847%	$219.273	$219.27	$219.25	$219.30
Purchase #2	$30.65	6.301%	$32.5813	$32.58	$32.60	$32.60
Purchase #3	$186.91	11.615%	$208.6196	$208.62	$208.60	$208.60
Purchase #4	$37.86	7.527%	$40.7097	$40.71	$40.70	$40.70
Purchase #5	$210.59	9.261%	$230.0927	$230.09	$230.10	$230.10
Purchase #6	$219.94	9.362%	$240.5308	$240.53	$240.55	$240.50
Purchase #7	$62.25	3.184%	$64.232	$64.23	$64.25	$64.20
7 purchase totals =	$942.51		$1,036.0391	$1,036.03	$1,036.05	$1,036.00