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	$192.26	5.404%	$202.6497	$202.65	$202.65	$202.60
Purchase #2	$16.78	7.362%	$18.0153	$18.02	$18.00	$18.00
Purchase #3	$54.51	4.303%	$56.8556	$56.86	$56.85	$56.90
Purchase #4	$55.63	10.217%	$61.3137	$61.31	$61.30	$61.30
Purchase #5	$79.42	4.748%	$83.1909	$83.19	$83.20	$83.20
Purchase #6	$100.67	11.565%	$112.3125	$112.31	$112.30	$112.30
Purchase #7	$85.75	5.847%	$90.7638	$90.76	$90.75	$90.80
7 purchase totals =	$585.02		$625.1015	$625.10	$625.05	$625.10