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	$240.69	5.832%	$254.727	$254.73	$254.75	$254.70
Purchase #2	$99.31	13.846%	$113.0605	$113.06	$113.05	$113.10
Purchase #3	$57.63	3.334%	$59.5514	$59.55	$59.55	$59.60
Purchase #4	$139.91	13.129%	$158.2788	$158.28	$158.30	$158.30
Purchase #5	$205.36	6.871%	$219.4703	$219.47	$219.45	$219.50
Purchase #6	$105.28	12.639%	$118.5863	$118.59	$118.60	$118.60
Purchase #7	$92.51	9.113%	$100.9404	$100.94	$100.95	$100.90
7 purchase totals =	$940.69		$1,024.6147	$1,024.62	$1,024.65	$1,024.70