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	$190.90	9.261%	$208.5792	$208.58	$208.60	$208.60
Purchase #2	$117.65	12.674%	$132.561	$132.56	$132.55	$132.60
Purchase #3	$212.85	10.481%	$235.1588	$235.16	$235.15	$235.20
Purchase #4	$38.54	12.585%	$43.3903	$43.39	$43.40	$43.40
Purchase #5	$49.69	7.677%	$53.5047	$53.50	$53.50	$53.50
Purchase #6	$127.64	3.868%	$132.5771	$132.58	$132.60	$132.60
Purchase #7	$209.95	9.128%	$229.1142	$229.11	$229.10	$229.10
7 purchase totals =	$947.22		$1,034.8853	$1,034.88	$1,034.90	$1,035.00