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	$240.28	4.727%	$251.638	$251.64	$251.65	$251.60
Purchase #2	$19.78	4.825%	$20.7344	$20.73	$20.75	$20.70
Purchase #3	$84.76	6.743%	$90.4754	$90.48	$90.50	$90.50
Purchase #4	$214.27	4.255%	$223.3872	$223.39	$223.40	$223.40
Purchase #5	$249.77	13.422%	$283.2941	$283.29	$283.30	$283.30
Purchase #6	$187.49	6.838%	$200.3106	$200.31	$200.30	$200.30
Purchase #7	$53.70	13.363%	$60.8759	$60.88	$60.90	$60.90
7 purchase totals =	$1,050.05		$1,130.7156	$1,130.72	$1,130.80	$1,130.70