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	$196.84	9.617%	$215.7701	$215.77	$215.75	$215.80
Purchase #2	$183.36	12.510%	$206.2983	$206.30	$206.30	$206.30
Purchase #3	$200.32	10.303%	$220.959	$220.96	$220.95	$221.00
Purchase #4	$56.74	4.274%	$59.1651	$59.17	$59.15	$59.20
Purchase #5	$49.72	9.476%	$54.4315	$54.43	$54.45	$54.40
Purchase #6	$68.31	6.371%	$72.662	$72.66	$72.65	$72.70
Purchase #7	$203.73	11.144%	$226.4337	$226.43	$226.45	$226.40
7 purchase totals =	$959.02		$1,055.7197	$1,055.72	$1,055.70	$1,055.80