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	$194.94	5.860%	$206.3635	$206.36	$206.35	$206.40
Purchase #2	$229.47	10.365%	$253.2546	$253.25	$253.25	$253.30
Purchase #3	$66.65	7.382%	$71.5701	$71.57	$71.55	$71.60
Purchase #4	$141.85	7.567%	$152.5838	$152.58	$152.60	$152.60
Purchase #5	$68.43	6.565%	$72.9224	$72.92	$72.90	$72.90
Purchase #6	$17.84	9.399%	$19.5168	$19.52	$19.50	$19.50
Purchase #7	$243.71	13.419%	$276.4134	$276.41	$276.40	$276.40
7 purchase totals =	$962.89		$1,052.6246	$1,052.61	$1,052.55	$1,052.70