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	$219.70	11.308%	$244.5437	$244.54	$244.55	$244.50
Purchase #2	$35.43	7.686%	$38.1531	$38.15	$38.15	$38.20
Purchase #3	$91.42	10.312%	$100.8472	$100.85	$100.85	$100.80
Purchase #4	$136.59	5.660%	$144.321	$144.32	$144.30	$144.30
Purchase #5	$101.47	11.852%	$113.4962	$113.50	$113.50	$113.50
Purchase #6	$98.92	7.846%	$106.6813	$106.68	$106.70	$106.70
Purchase #7	$247.83	7.472%	$266.3479	$266.35	$266.35	$266.30
7 purchase totals =	$931.36		$1,014.3904	$1,014.39	$1,014.40	$1,014.30