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	$38.66	7.188%	$41.4389	$41.44	$41.45	$41.40
Purchase #2	$149.55	7.515%	$160.7887	$160.79	$160.80	$160.80
Purchase #3	$105.57	3.145%	$108.8902	$108.89	$108.90	$108.90
Purchase #4	$119.78	13.788%	$136.2953	$136.30	$136.30	$136.30
Purchase #5	$171.81	7.784%	$185.1837	$185.18	$185.20	$185.20
Purchase #6	$165.81	5.111%	$174.2845	$174.28	$174.30	$174.30
Purchase #7	$131.90	9.839%	$144.8776	$144.88	$144.90	$144.90
7 purchase totals =	$883.08		$951.7589	$951.76	$951.85	$951.80