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	$233.94	8.621%	$254.108	$254.11	$254.10	$254.10
Purchase #2	$91.45	5.361%	$96.3526	$96.35	$96.35	$96.40
Purchase #3	$30.96	6.735%	$33.0452	$33.05	$33.05	$33.00
Purchase #4	$38.37	6.854%	$40.9999	$41.00	$41.00	$41.00
Purchase #5	$67.39	7.265%	$72.2859	$72.29	$72.30	$72.30
Purchase #6	$186.28	5.724%	$196.9427	$196.94	$196.95	$196.90
Purchase #7	$55.38	12.843%	$62.4925	$62.49	$62.50	$62.50
7 purchase totals =	$703.77		$756.2268	$756.23	$756.25	$756.20