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	$210.26	4.527%	$219.7785	$219.78	$219.80	$219.80
Purchase #2	$229.41	4.121%	$238.864	$238.86	$238.85	$238.90
Purchase #3	$97.60	7.130%	$104.5589	$104.56	$104.55	$104.60
Purchase #4	$148.45	4.110%	$154.5513	$154.55	$154.55	$154.60
Purchase #5	$177.65	3.308%	$183.5267	$183.53	$183.55	$183.50
Purchase #6	$148.35	3.483%	$153.517	$153.52	$153.50	$153.50
Purchase #7	$54.77	8.268%	$59.2984	$59.30	$59.30	$59.30
7 purchase totals =	$1,066.49		$1,114.0948	$1,114.10	$1,114.10	$1,114.20