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	$213.64	11.337%	$237.8604	$237.86	$237.85	$237.90
Purchase #2	$16.59	10.437%	$18.3215	$18.32	$18.30	$18.30
Purchase #3	$189.66	3.650%	$196.5826	$196.58	$196.60	$196.60
Purchase #4	$208.28	3.848%	$216.2946	$216.29	$216.30	$216.30
Purchase #5	$26.28	5.115%	$27.6242	$27.62	$27.60	$27.60
Purchase #6	$19.40	6.197%	$20.6022	$20.60	$20.60	$20.60
Purchase #7	$18.45	13.363%	$20.9155	$20.92	$20.90	$20.90
7 purchase totals =	$692.30		$738.2010	$738.19	$738.15	$738.20