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	$201.55	11.870%	$225.474	$225.47	$225.45	$225.50
Purchase #2	$94.45	3.371%	$97.6339	$97.63	$97.65	$97.60
Purchase #3	$104.28	6.408%	$110.9623	$110.96	$110.95	$111.00
Purchase #4	$19.30	11.388%	$21.4979	$21.50	$21.50	$21.50
Purchase #5	$21.73	5.178%	$22.8552	$22.86	$22.85	$22.90
Purchase #6	$68.30	7.600%	$73.4908	$73.49	$73.50	$73.50
Purchase #7	$18.39	11.254%	$20.4596	$20.46	$20.45	$20.50
7 purchase totals =	$528.00		$572.3737	$572.37	$572.35	$572.50