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	$157.83	11.354%	$175.75	$175.75	$175.75	$175.80
Purchase #2	$181.47	7.834%	$195.6864	$195.69	$195.70	$195.70
Purchase #3	$170.27	8.810%	$185.2708	$185.27	$185.25	$185.30
Purchase #4	$168.52	3.151%	$173.8301	$173.83	$173.85	$173.80
Purchase #5	$102.49	13.760%	$116.5926	$116.59	$116.60	$116.60
Purchase #6	$227.91	10.271%	$251.3186	$251.32	$251.30	$251.30
Purchase #7	$110.84	11.749%	$123.8626	$123.86	$123.85	$123.90
7 purchase totals =	$1,119.33		$1,222.3111	$1,222.31	$1,222.30	$1,222.40