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	$196.71	9.477%	$215.3522	$215.35	$215.35	$215.40
Purchase #2	$17.42	9.754%	$19.1191	$19.12	$19.10	$19.10
Purchase #3	$82.90	7.853%	$89.4101	$89.41	$89.40	$89.40
Purchase #4	$68.40	8.142%	$73.9691	$73.97	$73.95	$74.00
Purchase #5	$154.54	11.738%	$172.6799	$172.68	$172.70	$172.70
Purchase #6	$185.47	3.129%	$191.2734	$191.27	$191.25	$191.30
Purchase #7	$203.84	10.654%	$225.5571	$225.56	$225.55	$225.60
7 purchase totals =	$909.28		$987.3609	$987.36	$987.30	$987.50