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	$228.77	6.801%	$244.3286	$244.33	$244.35	$244.30
Purchase #2	$233.43	12.686%	$263.0429	$263.04	$263.05	$263.00
Purchase #3	$73.50	13.647%	$83.5305	$83.53	$83.55	$83.50
Purchase #4	$114.46	10.652%	$126.6523	$126.65	$126.65	$126.70
Purchase #5	$13.39	5.483%	$14.1242	$14.12	$14.10	$14.10
Purchase #6	$207.87	11.854%	$232.5109	$232.51	$232.50	$232.50
Purchase #7	$47.37	10.435%	$52.3131	$52.31	$52.30	$52.30
7 purchase totals =	$918.79		$1,016.5025	$1,016.49	$1,016.50	$1,016.40