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	$188.41	4.551%	$196.9845	$196.98	$197.00	$197.00
Purchase #2	$66.30	10.344%	$73.1581	$73.16	$73.15	$73.20
Purchase #3	$83.89	6.384%	$89.2455	$89.25	$89.25	$89.20
Purchase #4	$92.86	6.301%	$98.7111	$98.71	$98.70	$98.70
Purchase #5	$196.91	5.393%	$207.5294	$207.53	$207.55	$207.50
Purchase #6	$212.65	9.800%	$233.4897	$233.49	$233.50	$233.50
Purchase #7	$197.33	13.557%	$224.082	$224.08	$224.10	$224.10
7 purchase totals =	$1,038.35		$1,123.2003	$1,123.20	$1,123.25	$1,123.20