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	$183.30	7.446%	$196.9485	$196.95	$196.95	$196.90
Purchase #2	$89.54	12.111%	$100.3842	$100.38	$100.40	$100.40
Purchase #3	$179.96	6.162%	$191.0491	$191.05	$191.05	$191.00
Purchase #4	$133.65	9.601%	$146.4817	$146.48	$146.50	$146.50
Purchase #5	$71.25	7.118%	$76.3216	$76.32	$76.30	$76.30
Purchase #6	$211.34	9.481%	$231.3771	$231.38	$231.40	$231.40
Purchase #7	$242.87	8.632%	$263.8345	$263.83	$263.85	$263.80
7 purchase totals =	$1,111.91		$1,206.3967	$1,206.39	$1,206.45	$1,206.30