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	$58.57	4.774%	$61.3661	$61.37	$61.35	$61.40
Purchase #2	$94.89	8.450%	$102.9082	$102.91	$102.90	$102.90
Purchase #3	$11.37	6.757%	$12.1383	$12.14	$12.15	$12.10
Purchase #4	$153.72	5.132%	$161.6089	$161.61	$161.60	$161.60
Purchase #5	$91.82	3.607%	$95.1319	$95.13	$95.15	$95.10
Purchase #6	$222.92	7.776%	$240.2543	$240.25	$240.25	$240.30
Purchase #7	$54.64	7.705%	$58.85	$58.85	$58.85	$58.90
7 purchase totals =	$687.93		$732.2577	$732.26	$732.25	$732.30