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	$103.55	8.199%	$112.0401	$112.04	$112.05	$112.00
Purchase #2	$242.93	4.536%	$253.9493	$253.95	$253.95	$253.90
Purchase #3	$171.37	13.753%	$194.9385	$194.94	$194.95	$194.90
Purchase #4	$104.66	4.538%	$109.4095	$109.41	$109.40	$109.40
Purchase #5	$16.35	11.439%	$18.2203	$18.22	$18.20	$18.20
Purchase #6	$88.26	4.828%	$92.5212	$92.52	$92.50	$92.50
Purchase #7	$233.29	3.533%	$241.5321	$241.53	$241.55	$241.50
7 purchase totals =	$960.41		$1,022.6110	$1,022.61	$1,022.60	$1,022.40