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	$243.39	7.240%	$261.0114	$261.01	$261.00	$261.00
Purchase #2	$176.26	7.130%	$188.8273	$188.83	$188.85	$188.80
Purchase #3	$181.60	4.772%	$190.266	$190.27	$190.25	$190.30
Purchase #4	$134.27	7.817%	$144.7659	$144.77	$144.75	$144.80
Purchase #5	$137.42	6.296%	$146.072	$146.07	$146.05	$146.10
Purchase #6	$130.48	11.801%	$145.8779	$145.88	$145.90	$145.90
Purchase #7	$118.91	12.272%	$133.5026	$133.50	$133.50	$133.50
7 purchase totals =	$1,122.33		$1,210.3231	$1,210.33	$1,210.30	$1,210.40