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	$236.85	3.374%	$244.8413	$244.84	$244.85	$244.80
Purchase #2	$18.56	10.873%	$20.578	$20.58	$20.60	$20.60
Purchase #3	$153.39	7.817%	$165.3805	$165.38	$165.40	$165.40
Purchase #4	$38.31	11.711%	$42.7965	$42.80	$42.80	$42.80
Purchase #5	$110.62	11.437%	$123.2716	$123.27	$123.25	$123.30
Purchase #6	$178.25	12.742%	$200.9626	$200.96	$200.95	$201.00
Purchase #7	$144.66	6.301%	$153.775	$153.78	$153.80	$153.80
7 purchase totals =	$880.64		$951.6055	$951.61	$951.65	$951.70