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	$39.28	13.448%	$44.5624	$44.56	$44.55	$44.60
Purchase #2	$16.25	6.451%	$17.2983	$17.30	$17.30	$17.30
Purchase #3	$191.91	12.685%	$216.2538	$216.25	$216.25	$216.30
Purchase #4	$126.78	3.740%	$131.5216	$131.52	$131.50	$131.50
Purchase #5	$211.58	11.493%	$235.8969	$235.90	$235.90	$235.90
Purchase #6	$223.57	9.215%	$244.172	$244.17	$244.15	$244.20
Purchase #7	$242.45	12.311%	$272.298	$272.30	$272.30	$272.30
7 purchase totals =	$1,051.82		$1,162.0030	$1,162.00	$1,161.95	$1,162.10