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	$238.70	10.618%	$264.0452	$264.05	$264.05	$264.00
Purchase #2	$115.87	9.667%	$127.0712	$127.07	$127.05	$127.10
Purchase #3	$89.89	5.828%	$95.1288	$95.13	$95.15	$95.10
Purchase #4	$227.28	8.819%	$247.3238	$247.32	$247.30	$247.30
Purchase #5	$120.47	13.338%	$136.5383	$136.54	$136.55	$136.50
Purchase #6	$133.40	12.809%	$150.4872	$150.49	$150.50	$150.50
Purchase #7	$100.32	4.269%	$104.6027	$104.60	$104.60	$104.60
7 purchase totals =	$1,025.93		$1,125.1972	$1,125.20	$1,125.20	$1,125.10