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	$214.88	11.250%	$239.054	$239.05	$239.05	$239.10
Purchase #2	$64.26	5.727%	$67.9402	$67.94	$67.95	$67.90
Purchase #3	$181.62	5.567%	$191.7308	$191.73	$191.75	$191.70
Purchase #4	$148.83	11.449%	$165.8695	$165.87	$165.85	$165.90
Purchase #5	$105.83	3.329%	$109.3531	$109.35	$109.35	$109.40
Purchase #6	$59.67	10.519%	$65.9467	$65.95	$65.95	$65.90
Purchase #7	$205.36	10.608%	$227.1446	$227.14	$227.15	$227.10
7 purchase totals =	$980.45		$1,067.0389	$1,067.03	$1,067.05	$1,067.00