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	$182.92	7.110%	$195.9256	$195.93	$195.95	$195.90
Purchase #2	$216.25	10.129%	$238.154	$238.15	$238.15	$238.20
Purchase #3	$17.72	10.686%	$19.6136	$19.61	$19.60	$19.60
Purchase #4	$99.92	4.810%	$104.7262	$104.73	$104.75	$104.70
Purchase #5	$153.66	13.641%	$174.6208	$174.62	$174.60	$174.60
Purchase #6	$134.65	5.759%	$142.4045	$142.40	$142.40	$142.40
Purchase #7	$200.49	12.272%	$225.0941	$225.09	$225.10	$225.10
7 purchase totals =	$1,005.61		$1,100.5388	$1,100.53	$1,100.55	$1,100.50