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	$161.83	10.317%	$178.526	$178.53	$178.55	$178.50
Purchase #2	$160.56	13.482%	$182.2067	$182.21	$182.20	$182.20
Purchase #3	$248.42	13.138%	$281.0574	$281.06	$281.05	$281.10
Purchase #4	$14.98	8.450%	$16.2458	$16.25	$16.25	$16.20
Purchase #5	$156.42	4.112%	$162.852	$162.85	$162.85	$162.90
Purchase #6	$123.57	7.734%	$133.1269	$133.13	$133.15	$133.10
Purchase #7	$92.61	7.463%	$99.5215	$99.52	$99.50	$99.50
7 purchase totals =	$958.39		$1,053.5363	$1,053.55	$1,053.55	$1,053.50