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	$85.98	6.487%	$91.5575	$91.56	$91.55	$91.60
Purchase #2	$126.93	4.841%	$133.0747	$133.07	$133.05	$133.10
Purchase #3	$92.92	4.689%	$97.277	$97.28	$97.30	$97.30
Purchase #4	$10.33	5.266%	$10.874	$10.87	$10.85	$10.90
Purchase #5	$78.56	9.321%	$85.8826	$85.88	$85.90	$85.90
Purchase #6	$91.28	9.798%	$100.2236	$100.22	$100.20	$100.20
Purchase #7	$249.29	11.280%	$277.4099	$277.41	$277.40	$277.40
7 purchase totals =	$735.29		$796.2993	$796.29	$796.25	$796.40