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	$212.89	5.823%	$225.2866	$225.29	$225.30	$225.30
Purchase #2	$96.64	4.299%	$100.7946	$100.79	$100.80	$100.80
Purchase #3	$36.64	13.784%	$41.6905	$41.69	$41.70	$41.70
Purchase #4	$217.48	10.524%	$240.3676	$240.37	$240.35	$240.40
Purchase #5	$164.73	8.409%	$178.5821	$178.58	$178.60	$178.60
Purchase #6	$18.91	8.213%	$20.4631	$20.46	$20.45	$20.50
Purchase #7	$212.77	12.224%	$238.779	$238.78	$238.80	$238.80
7 purchase totals =	$960.06		$1,045.9635	$1,045.96	$1,046.00	$1,046.10