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	$143.47	5.212%	$150.9477	$150.95	$150.95	$150.90
Purchase #2	$193.29	10.669%	$213.9121	$213.91	$213.90	$213.90
Purchase #3	$68.67	6.689%	$73.2633	$73.26	$73.25	$73.30
Purchase #4	$111.67	4.211%	$116.3724	$116.37	$116.35	$116.40
Purchase #5	$73.92	6.447%	$78.6856	$78.69	$78.70	$78.70
Purchase #6	$191.73	12.668%	$216.0184	$216.02	$216.00	$216.00
Purchase #7	$164.85	11.719%	$184.1688	$184.17	$184.15	$184.20
7 purchase totals =	$947.60		$1,033.3683	$1,033.37	$1,033.30	$1,033.40