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	$195.88	9.240%	$213.9793	$213.98	$214.00	$214.00
Purchase #2	$81.44	11.136%	$90.5092	$90.51	$90.50	$90.50
Purchase #3	$50.83	3.768%	$52.7453	$52.75	$52.75	$52.70
Purchase #4	$132.52	11.166%	$147.3172	$147.32	$147.30	$147.30
Purchase #5	$212.44	7.495%	$228.3624	$228.36	$228.35	$228.40
Purchase #6	$59.89	7.105%	$64.1452	$64.15	$64.15	$64.10
Purchase #7	$177.74	10.636%	$196.6444	$196.64	$196.65	$196.60
7 purchase totals =	$910.74		$993.7030	$993.71	$993.70	$993.60