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	$244.83	8.472%	$265.572	$265.57	$265.55	$265.60
Purchase #2	$89.75	7.327%	$96.326	$96.33	$96.35	$96.30
Purchase #3	$154.83	7.420%	$166.3184	$166.32	$166.30	$166.30
Purchase #4	$132.85	6.722%	$141.7802	$141.78	$141.80	$141.80
Purchase #5	$37.45	9.213%	$40.9003	$40.90	$40.90	$40.90
Purchase #6	$106.35	9.782%	$116.7532	$116.75	$116.75	$116.80
Purchase #7	$170.27	7.113%	$182.3813	$182.38	$182.40	$182.40
7 purchase totals =	$936.33		$1,010.0314	$1,010.03	$1,010.05	$1,010.10