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	$123.97	3.254%	$128.004	$128.00	$128.00	$128.00
Purchase #2	$24.56	4.796%	$25.7379	$25.74	$25.75	$25.70
Purchase #3	$105.64	10.382%	$116.6075	$116.61	$116.60	$116.60
Purchase #4	$107.73	3.189%	$111.1655	$111.17	$111.15	$111.20
Purchase #5	$54.41	9.205%	$59.4184	$59.42	$59.40	$59.40
Purchase #6	$205.72	3.272%	$212.4512	$212.45	$212.45	$212.50
Purchase #7	$201.76	10.115%	$222.168	$222.17	$222.15	$222.20
7 purchase totals =	$823.79		$875.5525	$875.56	$875.50	$875.60