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	$141.64	4.463%	$147.9614	$147.96	$147.95	$148.00
Purchase #2	$64.80	3.428%	$67.0213	$67.02	$67.00	$67.00
Purchase #3	$168.66	12.844%	$190.3227	$190.32	$190.30	$190.30
Purchase #4	$185.73	9.513%	$203.3985	$203.40	$203.40	$203.40
Purchase #5	$160.65	4.675%	$168.1604	$168.16	$168.15	$168.20
Purchase #6	$40.88	6.434%	$43.5102	$43.51	$43.50	$43.50
Purchase #7	$120.58	5.832%	$127.6122	$127.61	$127.60	$127.60
7 purchase totals =	$882.94		$947.9867	$947.98	$947.90	$948.00