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	$41.51	3.680%	$43.0376	$43.04	$43.05	$43.00
Purchase #2	$54.48	9.252%	$59.5205	$59.52	$59.50	$59.50
Purchase #3	$219.59	4.589%	$229.667	$229.67	$229.65	$229.70
Purchase #4	$29.91	9.418%	$32.7269	$32.73	$32.75	$32.70
Purchase #5	$44.85	5.105%	$47.1396	$47.14	$47.15	$47.10
Purchase #6	$49.41	3.432%	$51.1058	$51.11	$51.10	$51.10
Purchase #7	$221.49	10.293%	$244.288	$244.29	$244.30	$244.30
7 purchase totals =	$661.24		$707.4854	$707.50	$707.50	$707.40