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	$106.95	10.204%	$117.8632	$117.86	$117.85	$117.90
Purchase #2	$30.76	3.227%	$31.7526	$31.75	$31.75	$31.80
Purchase #3	$99.73	13.624%	$113.3172	$113.32	$113.30	$113.30
Purchase #4	$180.80	7.661%	$194.6511	$194.65	$194.65	$194.70
Purchase #5	$112.30	13.533%	$127.4976	$127.50	$127.50	$127.50
Purchase #6	$174.32	13.865%	$198.4895	$198.49	$198.50	$198.50
Purchase #7	$203.62	7.827%	$219.5573	$219.56	$219.55	$219.60
7 purchase totals =	$908.48		$1,003.1285	$1,003.13	$1,003.10	$1,003.30