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	$41.90	11.345%	$46.6536	$46.65	$46.65	$46.70
Purchase #2	$247.44	4.528%	$258.6441	$258.64	$258.65	$258.60
Purchase #3	$40.50	7.324%	$43.4662	$43.47	$43.45	$43.50
Purchase #4	$174.91	6.543%	$186.3544	$186.35	$186.35	$186.40
Purchase #5	$192.50	4.119%	$200.4291	$200.43	$200.45	$200.40
Purchase #6	$52.55	13.258%	$59.5171	$59.52	$59.50	$59.50
Purchase #7	$167.81	3.186%	$173.1564	$173.16	$173.15	$173.20
7 purchase totals =	$917.61		$968.2209	$968.22	$968.20	$968.30