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	$196.36	6.533%	$209.1882	$209.19	$209.20	$209.20
Purchase #2	$54.60	7.141%	$58.499	$58.50	$58.50	$58.50
Purchase #3	$102.53	6.290%	$108.9791	$108.98	$109.00	$109.00
Purchase #4	$179.85	3.514%	$186.1699	$186.17	$186.15	$186.20
Purchase #5	$89.53	11.186%	$99.5448	$99.54	$99.55	$99.50
Purchase #6	$29.34	4.105%	$30.5444	$30.54	$30.55	$30.50
Purchase #7	$27.61	10.600%	$30.5367	$30.54	$30.55	$30.50
7 purchase totals =	$679.82		$723.4621	$723.46	$723.50	$723.40