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	$217.64	11.497%	$242.6621	$242.66	$242.65	$242.70
Purchase #2	$5.85	10.384%	$6.4575	$6.46	$6.45	$6.50
Purchase #3	$53.87	4.253%	$56.1611	$56.16	$56.15	$56.20
Purchase #4	$175.52	5.816%	$185.7282	$185.73	$185.75	$185.70
Purchase #5	$140.82	5.467%	$148.5186	$148.52	$148.50	$148.50
Purchase #6	$150.98	11.228%	$167.932	$167.93	$167.95	$167.90
Purchase #7	$226.82	13.769%	$258.0508	$258.05	$258.05	$258.10
7 purchase totals =	$971.50		$1,065.5103	$1,065.51	$1,065.50	$1,065.60