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	$148.45	3.635%	$153.8462	$153.85	$153.85	$153.80
Purchase #2	$176.92	11.203%	$196.7403	$196.74	$196.75	$196.70
Purchase #3	$53.47	3.867%	$55.5377	$55.54	$55.55	$55.50
Purchase #4	$135.41	11.241%	$150.6314	$150.63	$150.65	$150.60
Purchase #5	$190.93	10.486%	$210.9509	$210.95	$210.95	$211.00
Purchase #6	$242.26	4.395%	$252.9073	$252.91	$252.90	$252.90
Purchase #7	$40.37	11.590%	$45.0489	$45.05	$45.05	$45.00
7 purchase totals =	$987.81		$1,065.6627	$1,065.67	$1,065.70	$1,065.50