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	$167.59	10.772%	$185.6428	$185.64	$185.65	$185.60
Purchase #2	$11.57	11.513%	$12.9021	$12.90	$12.90	$12.90
Purchase #3	$150.47	3.183%	$155.2595	$155.26	$155.25	$155.30
Purchase #4	$145.39	5.405%	$153.2483	$153.25	$153.25	$153.20
Purchase #5	$230.65	11.590%	$257.3823	$257.38	$257.40	$257.40
Purchase #6	$141.88	12.450%	$159.5441	$159.54	$159.55	$159.50
Purchase #7	$83.26	8.304%	$90.1739	$90.17	$90.15	$90.20
7 purchase totals =	$930.81		$1,014.1530	$1,014.14	$1,014.15	$1,014.10