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	$12.91	10.196%	$14.2263	$14.23	$14.25	$14.20
Purchase #2	$89.94	13.404%	$101.9956	$102.00	$102.00	$102.00
Purchase #3	$17.29	5.219%	$18.1924	$18.19	$18.20	$18.20
Purchase #4	$158.91	5.604%	$167.8153	$167.82	$167.80	$167.80
Purchase #5	$147.89	11.724%	$165.2286	$165.23	$165.25	$165.20
Purchase #6	$43.75	3.213%	$45.1557	$45.16	$45.15	$45.20
Purchase #7	$103.75	5.871%	$109.8412	$109.84	$109.85	$109.80
7 purchase totals =	$574.44		$622.4551	$622.47	$622.50	$622.40