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	$165.49	5.146%	$174.0061	$174.01	$174.00	$174.00
Purchase #2	$179.27	8.236%	$194.0347	$194.03	$194.05	$194.00
Purchase #3	$39.38	10.694%	$43.5913	$43.59	$43.60	$43.60
Purchase #4	$145.88	7.378%	$156.643	$156.64	$156.65	$156.60
Purchase #5	$140.67	4.249%	$146.6471	$146.65	$146.65	$146.60
Purchase #6	$134.90	7.461%	$144.9649	$144.96	$144.95	$145.00
Purchase #7	$141.80	12.449%	$159.4527	$159.45	$159.45	$159.50
7 purchase totals =	$947.39		$1,019.3398	$1,019.33	$1,019.35	$1,019.30