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	$13.65	4.692%	$14.2905	$14.29	$14.30	$14.30
Purchase #2	$75.64	12.809%	$85.3287	$85.33	$85.35	$85.30
Purchase #3	$224.98	5.574%	$237.5204	$237.52	$237.50	$237.50
Purchase #4	$202.34	4.318%	$211.077	$211.08	$211.10	$211.10
Purchase #5	$244.68	4.484%	$255.6515	$255.65	$255.65	$255.70
Purchase #6	$93.74	6.570%	$99.8987	$99.90	$99.90	$99.90
Purchase #7	$100.57	9.153%	$109.7752	$109.78	$109.80	$109.80
7 purchase totals =	$955.60		$1,013.5420	$1,013.55	$1,013.60	$1,013.60