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	$187.77	4.857%	$196.89	$196.89	$196.90	$196.90
Purchase #2	$188.70	12.224%	$211.7667	$211.77	$211.75	$211.80
Purchase #3	$239.64	9.169%	$261.6126	$261.61	$261.60	$261.60
Purchase #4	$58.63	4.271%	$61.1341	$61.13	$61.15	$61.10
Purchase #5	$77.46	6.222%	$82.2796	$82.28	$82.30	$82.30
Purchase #6	$204.79	3.773%	$212.5167	$212.52	$212.50	$212.50
Purchase #7	$121.51	4.391%	$126.8455	$126.85	$126.85	$126.80
7 purchase totals =	$1,078.50		$1,153.0452	$1,153.05	$1,153.05	$1,153.00