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	$191.31	3.568%	$198.1359	$198.14	$198.15	$198.10
Purchase #2	$154.33	8.772%	$167.8678	$167.87	$167.85	$167.90
Purchase #3	$40.76	6.710%	$43.495	$43.50	$43.50	$43.50
Purchase #4	$219.39	13.697%	$249.4398	$249.44	$249.45	$249.40
Purchase #5	$174.47	12.638%	$196.5195	$196.52	$196.50	$196.50
Purchase #6	$107.37	4.721%	$112.4389	$112.44	$112.45	$112.40
Purchase #7	$193.60	9.174%	$211.3609	$211.36	$211.35	$211.40
7 purchase totals =	$1,081.23		$1,179.2578	$1,179.27	$1,179.25	$1,179.20