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	$59.53	10.406%	$65.7247	$65.72	$65.70	$65.70
Purchase #2	$209.70	13.488%	$237.9843	$237.98	$238.00	$238.00
Purchase #3	$185.76	7.734%	$200.1267	$200.13	$200.15	$200.10
Purchase #4	$105.51	9.503%	$115.5366	$115.54	$115.55	$115.50
Purchase #5	$180.32	5.601%	$190.4197	$190.42	$190.40	$190.40
Purchase #6	$148.29	6.693%	$158.215	$158.22	$158.20	$158.20
Purchase #7	$192.45	3.409%	$199.0106	$199.01	$199.00	$199.00
7 purchase totals =	$1,081.56		$1,167.0176	$1,167.02	$1,167.00	$1,166.90