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	$109.72	13.567%	$124.6057	$124.61	$124.60	$124.60
Purchase #2	$110.42	3.465%	$114.2461	$114.25	$114.25	$114.20
Purchase #3	$58.84	4.296%	$61.3678	$61.37	$61.35	$61.40
Purchase #4	$111.76	10.406%	$123.3897	$123.39	$123.40	$123.40
Purchase #5	$191.36	10.721%	$211.8757	$211.88	$211.90	$211.90
Purchase #6	$202.52	8.329%	$219.3879	$219.39	$219.40	$219.40
Purchase #7	$183.45	5.457%	$193.4609	$193.46	$193.45	$193.50
7 purchase totals =	$968.07		$1,048.3338	$1,048.35	$1,048.35	$1,048.40