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	$215.48	10.565%	$238.2455	$238.25	$238.25	$238.20
Purchase #2	$224.28	10.718%	$248.3183	$248.32	$248.30	$248.30
Purchase #3	$176.56	7.746%	$190.2363	$190.24	$190.25	$190.20
Purchase #4	$96.51	7.843%	$104.0793	$104.08	$104.10	$104.10
Purchase #5	$162.72	5.750%	$172.0764	$172.08	$172.10	$172.10
Purchase #6	$185.62	3.185%	$191.532	$191.53	$191.55	$191.50
Purchase #7	$8.52	3.671%	$8.8328	$8.83	$8.85	$8.80
7 purchase totals =	$1,069.69		$1,153.3206	$1,153.33	$1,153.40	$1,153.20