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	$194.34	5.145%	$204.3388	$204.34	$204.35	$204.30
Purchase #2	$80.93	13.183%	$91.599	$91.60	$91.60	$91.60
Purchase #3	$137.93	10.859%	$152.9078	$152.91	$152.90	$152.90
Purchase #4	$67.49	10.225%	$74.3909	$74.39	$74.40	$74.40
Purchase #5	$162.71	9.629%	$178.3773	$178.38	$178.40	$178.40
Purchase #6	$249.57	13.177%	$282.4558	$282.46	$282.45	$282.50
Purchase #7	$103.94	7.608%	$111.8478	$111.85	$111.85	$111.80
7 purchase totals =	$996.91		$1,095.9174	$1,095.93	$1,095.95	$1,095.90