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	$107.91	3.814%	$112.0257	$112.03	$112.05	$112.00
Purchase #2	$225.74	3.412%	$233.4422	$233.44	$233.45	$233.40
Purchase #3	$242.78	4.786%	$254.3995	$254.40	$254.40	$254.40
Purchase #4	$136.28	8.539%	$147.9169	$147.92	$147.90	$147.90
Purchase #5	$100.97	3.820%	$104.8271	$104.83	$104.85	$104.80
Purchase #6	$99.85	9.547%	$109.3827	$109.38	$109.40	$109.40
Purchase #7	$51.94	7.313%	$55.7384	$55.74	$55.75	$55.70
7 purchase totals =	$965.47		$1,017.7325	$1,017.74	$1,017.80	$1,017.60