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	$89.86	7.475%	$96.577	$96.58	$96.60	$96.60
Purchase #2	$167.34	3.171%	$172.6464	$172.65	$172.65	$172.60
Purchase #3	$110.84	7.533%	$119.1896	$119.19	$119.20	$119.20
Purchase #4	$196.73	3.448%	$203.5133	$203.51	$203.50	$203.50
Purchase #5	$223.97	9.418%	$245.0635	$245.06	$245.05	$245.10
Purchase #6	$144.32	9.660%	$158.2613	$158.26	$158.25	$158.30
Purchase #7	$93.50	9.771%	$102.6359	$102.64	$102.65	$102.60
7 purchase totals =	$1,026.56		$1,097.8870	$1,097.89	$1,097.90	$1,097.90