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	$140.89	8.705%	$153.1545	$153.15	$153.15	$153.20
Purchase #2	$100.44	5.189%	$105.6518	$105.65	$105.65	$105.70
Purchase #3	$81.28	13.330%	$92.1146	$92.11	$92.10	$92.10
Purchase #4	$249.91	3.582%	$258.8618	$258.86	$258.85	$258.90
Purchase #5	$218.77	4.748%	$229.1572	$229.16	$229.15	$229.20
Purchase #6	$74.83	8.765%	$81.3888	$81.39	$81.40	$81.40
Purchase #7	$112.81	13.268%	$127.7776	$127.78	$127.80	$127.80
7 purchase totals =	$978.93		$1,048.1063	$1,048.10	$1,048.10	$1,048.30