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	$160.55	13.358%	$181.9963	$182.00	$182.00	$182.00
Purchase #2	$83.93	9.153%	$91.6121	$91.61	$91.60	$91.60
Purchase #3	$105.32	13.571%	$119.613	$119.61	$119.60	$119.60
Purchase #4	$164.98	11.451%	$183.8719	$183.87	$183.85	$183.90
Purchase #5	$33.37	11.817%	$37.3133	$37.31	$37.30	$37.30
Purchase #6	$243.31	6.832%	$259.9329	$259.93	$259.95	$259.90
Purchase #7	$230.97	4.694%	$241.8117	$241.81	$241.80	$241.80
7 purchase totals =	$1,022.43		$1,116.1512	$1,116.14	$1,116.10	$1,116.10