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	$174.40	3.446%	$180.4098	$180.41	$180.40	$180.40
Purchase #2	$132.74	11.774%	$148.3688	$148.37	$148.35	$148.40
Purchase #3	$158.91	9.604%	$174.1717	$174.17	$174.15	$174.20
Purchase #4	$49.41	6.115%	$52.4314	$52.43	$52.45	$52.40
Purchase #5	$209.46	6.114%	$222.2664	$222.27	$222.25	$222.30
Purchase #6	$57.83	13.680%	$65.7411	$65.74	$65.75	$65.70
Purchase #7	$202.58	6.439%	$215.6241	$215.62	$215.60	$215.60
7 purchase totals =	$985.33		$1,059.0133	$1,059.01	$1,058.95	$1,059.00