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	$178.56	8.676%	$194.0519	$194.05	$194.05	$194.10
Purchase #2	$129.69	9.871%	$142.4917	$142.49	$142.50	$142.50
Purchase #3	$235.30	13.654%	$267.4279	$267.43	$267.45	$267.40
Purchase #4	$95.92	13.494%	$108.8634	$108.86	$108.85	$108.90
Purchase #5	$35.59	5.841%	$37.6688	$37.67	$37.65	$37.70
Purchase #6	$236.93	8.174%	$256.2967	$256.30	$256.30	$256.30
Purchase #7	$194.98	10.436%	$215.3281	$215.33	$215.35	$215.30
7 purchase totals =	$1,106.97		$1,222.1285	$1,222.13	$1,222.15	$1,222.20