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	$196.39	11.660%	$219.2891	$219.29	$219.30	$219.30
Purchase #2	$52.96	5.734%	$55.9967	$56.00	$56.00	$56.00
Purchase #3	$65.49	12.198%	$73.4785	$73.48	$73.50	$73.50
Purchase #4	$162.77	5.294%	$171.387	$171.39	$171.40	$171.40
Purchase #5	$233.51	13.793%	$265.718	$265.72	$265.70	$265.70
Purchase #6	$53.41	4.540%	$55.8348	$55.83	$55.85	$55.80
Purchase #7	$218.96	4.803%	$229.4766	$229.48	$229.50	$229.50
7 purchase totals =	$983.49		$1,071.1807	$1,071.19	$1,071.25	$1,071.20