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	$86.39	8.172%	$93.4498	$93.45	$93.45	$93.40
Purchase #2	$101.40	12.793%	$114.3721	$114.37	$114.35	$114.40
Purchase #3	$76.50	7.524%	$82.2559	$82.26	$82.25	$82.30
Purchase #4	$210.79	12.310%	$236.7382	$236.74	$236.75	$236.70
Purchase #5	$130.77	9.304%	$142.9368	$142.94	$142.95	$142.90
Purchase #6	$231.36	10.743%	$256.215	$256.22	$256.20	$256.20
Purchase #7	$157.58	10.836%	$174.6554	$174.66	$174.65	$174.70
7 purchase totals =	$994.79		$1,100.6232	$1,100.64	$1,100.60	$1,100.60