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	$192.78	6.705%	$205.7059	$205.71	$205.70	$205.70
Purchase #2	$51.91	8.446%	$56.2943	$56.29	$56.30	$56.30
Purchase #3	$50.92	5.163%	$53.549	$53.55	$53.55	$53.50
Purchase #4	$231.69	5.681%	$244.8523	$244.85	$244.85	$244.90
Purchase #5	$13.50	4.675%	$14.1311	$14.13	$14.15	$14.10
Purchase #6	$111.26	4.481%	$116.2456	$116.25	$116.25	$116.20
Purchase #7	$55.46	11.630%	$61.91	$61.91	$61.90	$61.90
7 purchase totals =	$707.52		$752.6882	$752.69	$752.70	$752.60