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	$53.27	13.501%	$60.462	$60.46	$60.45	$60.50
Purchase #2	$9.85	10.766%	$10.9105	$10.91	$10.90	$10.90
Purchase #3	$58.42	12.140%	$65.5122	$65.51	$65.50	$65.50
Purchase #4	$73.65	4.310%	$76.8243	$76.82	$76.80	$76.80
Purchase #5	$224.46	7.269%	$240.776	$240.78	$240.80	$240.80
Purchase #6	$11.80	9.386%	$12.9075	$12.91	$12.90	$12.90
Purchase #7	$238.32	3.812%	$247.4048	$247.40	$247.40	$247.40
7 purchase totals =	$669.77		$714.7973	$714.79	$714.75	$714.80