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	$50.87	10.369%	$56.1447	$56.14	$56.15	$56.10
Purchase #2	$233.60	13.648%	$265.4817	$265.48	$265.50	$265.50
Purchase #3	$79.69	5.489%	$84.0642	$84.06	$84.05	$84.10
Purchase #4	$225.94	7.498%	$242.881	$242.88	$242.90	$242.90
Purchase #5	$147.82	13.605%	$167.9309	$167.93	$167.95	$167.90
Purchase #6	$57.41	7.750%	$61.8593	$61.86	$61.85	$61.90
Purchase #7	$138.46	4.643%	$144.8887	$144.89	$144.90	$144.90
7 purchase totals =	$933.79		$1,023.2505	$1,023.24	$1,023.30	$1,023.30