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	$106.83	3.826%	$110.9173	$110.92	$110.90	$110.90
Purchase #2	$182.78	3.129%	$188.4992	$188.50	$188.50	$188.50
Purchase #3	$101.85	11.461%	$113.523	$113.52	$113.50	$113.50
Purchase #4	$208.31	11.114%	$231.4616	$231.46	$231.45	$231.50
Purchase #5	$94.51	5.316%	$99.5342	$99.53	$99.55	$99.50
Purchase #6	$101.72	11.243%	$113.1564	$113.16	$113.15	$113.20
Purchase #7	$247.61	8.188%	$267.8843	$267.88	$267.90	$267.90
7 purchase totals =	$1,043.61		$1,124.9760	$1,124.97	$1,124.95	$1,125.00