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	$152.69	3.520%	$158.0647	$158.06	$158.05	$158.10
Purchase #2	$11.90	13.582%	$13.5163	$13.52	$13.50	$13.50
Purchase #3	$82.97	3.477%	$85.8549	$85.85	$85.85	$85.90
Purchase #4	$21.62	7.251%	$23.1877	$23.19	$23.20	$23.20
Purchase #5	$233.30	9.618%	$255.7388	$255.74	$255.75	$255.70
Purchase #6	$141.73	6.354%	$150.7355	$150.74	$150.75	$150.70
Purchase #7	$80.86	10.253%	$89.1506	$89.15	$89.15	$89.20
7 purchase totals =	$725.07		$776.2485	$776.25	$776.25	$776.30