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	$158.48	3.781%	$164.4721	$164.47	$164.45	$164.50
Purchase #2	$117.66	11.412%	$131.0874	$131.09	$131.10	$131.10
Purchase #3	$135.59	3.808%	$140.7533	$140.75	$140.75	$140.80
Purchase #4	$238.42	3.784%	$247.4418	$247.44	$247.45	$247.40
Purchase #5	$127.34	3.353%	$131.6097	$131.61	$131.60	$131.60
Purchase #6	$136.87	12.278%	$153.6749	$153.67	$153.65	$153.70
Purchase #7	$116.28	8.687%	$126.3812	$126.38	$126.40	$126.40
7 purchase totals =	$1,030.64		$1,095.4204	$1,095.41	$1,095.40	$1,095.50