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	$114.69	5.565%	$121.0725	$121.07	$121.05	$121.10
Purchase #2	$106.90	6.864%	$114.2376	$114.24	$114.25	$114.20
Purchase #3	$40.40	4.738%	$42.3142	$42.31	$42.30	$42.30
Purchase #4	$53.27	11.842%	$59.5782	$59.58	$59.60	$59.60
Purchase #5	$226.25	6.429%	$240.7956	$240.80	$240.80	$240.80
Purchase #6	$208.33	5.477%	$219.7402	$219.74	$219.75	$219.70
Purchase #7	$204.86	5.376%	$215.8733	$215.87	$215.85	$215.90
7 purchase totals =	$954.70		$1,013.6116	$1,013.61	$1,013.60	$1,013.60