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	$104.65	6.115%	$111.0493	$111.05	$111.05	$111.00
Purchase #2	$148.59	10.324%	$163.9304	$163.93	$163.95	$163.90
Purchase #3	$41.86	8.329%	$45.3465	$45.35	$45.35	$45.30
Purchase #4	$162.74	12.521%	$183.1167	$183.12	$183.10	$183.10
Purchase #5	$137.28	12.518%	$154.4647	$154.46	$154.45	$154.50
Purchase #6	$147.41	10.502%	$162.891	$162.89	$162.90	$162.90
Purchase #7	$222.89	4.652%	$233.2588	$233.26	$233.25	$233.30
7 purchase totals =	$965.42		$1,054.0574	$1,054.06	$1,054.05	$1,054.00