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	$176.71	11.170%	$196.4485	$196.45	$196.45	$196.40
Purchase #2	$53.60	7.142%	$57.4281	$57.43	$57.45	$57.40
Purchase #3	$116.95	5.785%	$123.7156	$123.72	$123.70	$123.70
Purchase #4	$219.36	11.657%	$244.9308	$244.93	$244.95	$244.90
Purchase #5	$82.70	9.346%	$90.4291	$90.43	$90.45	$90.40
Purchase #6	$207.80	6.469%	$221.2426	$221.24	$221.25	$221.20
Purchase #7	$94.73	8.268%	$102.5623	$102.56	$102.55	$102.60
7 purchase totals =	$951.85		$1,036.7570	$1,036.76	$1,036.80	$1,036.60