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	$32.61	9.253%	$35.6274	$35.63	$35.65	$35.60
Purchase #2	$134.66	5.288%	$141.7808	$141.78	$141.80	$141.80
Purchase #3	$72.37	5.250%	$76.1694	$76.17	$76.15	$76.20
Purchase #4	$167.87	13.575%	$190.6584	$190.66	$190.65	$190.70
Purchase #5	$139.91	8.113%	$151.2609	$151.26	$151.25	$151.30
Purchase #6	$240.44	11.714%	$268.6051	$268.61	$268.60	$268.60
Purchase #7	$187.37	12.273%	$210.3659	$210.37	$210.35	$210.40
7 purchase totals =	$975.23		$1,074.4679	$1,074.48	$1,074.45	$1,074.60