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	$143.33	8.371%	$155.3282	$155.33	$155.35	$155.30
Purchase #2	$148.48	11.868%	$166.1016	$166.10	$166.10	$166.10
Purchase #3	$48.34	8.696%	$52.5436	$52.54	$52.55	$52.50
Purchase #4	$159.69	3.333%	$165.0125	$165.01	$165.00	$165.00
Purchase #5	$203.29	6.124%	$215.7395	$215.74	$215.75	$215.70
Purchase #6	$208.27	7.360%	$223.5987	$223.60	$223.60	$223.60
Purchase #7	$150.34	5.300%	$158.308	$158.31	$158.30	$158.30
7 purchase totals =	$1,061.74		$1,136.6321	$1,136.63	$1,136.65	$1,136.50