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	$211.61	5.558%	$223.3713	$223.37	$223.35	$223.40
Purchase #2	$196.40	9.675%	$215.4017	$215.40	$215.40	$215.40
Purchase #3	$167.75	13.314%	$190.0842	$190.08	$190.10	$190.10
Purchase #4	$47.39	10.764%	$52.4911	$52.49	$52.50	$52.50
Purchase #5	$59.87	13.677%	$68.0584	$68.06	$68.05	$68.10
Purchase #6	$97.33	10.383%	$107.4358	$107.44	$107.45	$107.40
Purchase #7	$146.37	11.229%	$162.8059	$162.81	$162.80	$162.80
7 purchase totals =	$926.72		$1,019.6484	$1,019.65	$1,019.65	$1,019.70