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	$140.35	5.412%	$147.9457	$147.95	$147.95	$147.90
Purchase #2	$173.59	10.248%	$191.3795	$191.38	$191.40	$191.40
Purchase #3	$40.55	6.253%	$43.0856	$43.09	$43.10	$43.10
Purchase #4	$214.58	8.567%	$232.9631	$232.96	$232.95	$233.00
Purchase #5	$235.32	11.512%	$262.41	$262.41	$262.40	$262.40
Purchase #6	$106.65	9.570%	$116.8564	$116.86	$116.85	$116.90
Purchase #7	$181.25	13.614%	$205.9254	$205.93	$205.95	$205.90
7 purchase totals =	$1,092.29		$1,200.5657	$1,200.58	$1,200.60	$1,200.60