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	$187.67	4.837%	$196.7476	$196.75	$196.75	$196.70
Purchase #2	$78.99	3.522%	$81.772	$81.77	$81.75	$81.80
Purchase #3	$100.33	11.383%	$111.7506	$111.75	$111.75	$111.80
Purchase #4	$103.77	13.421%	$117.697	$117.70	$117.70	$117.70
Purchase #5	$125.50	10.698%	$138.926	$138.93	$138.95	$138.90
Purchase #6	$185.86	4.411%	$194.0583	$194.06	$194.05	$194.10
Purchase #7	$226.53	10.442%	$250.1843	$250.18	$250.20	$250.20
7 purchase totals =	$1,008.65		$1,091.1358	$1,091.14	$1,091.15	$1,091.20