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	$193.29	11.441%	$215.4043	$215.40	$215.40	$215.40
Purchase #2	$14.43	5.773%	$15.263	$15.26	$15.25	$15.30
Purchase #3	$245.31	5.796%	$259.5282	$259.53	$259.55	$259.50
Purchase #4	$165.96	3.690%	$172.0839	$172.08	$172.10	$172.10
Purchase #5	$87.42	4.483%	$91.339	$91.34	$91.35	$91.30
Purchase #6	$213.89	11.515%	$238.5194	$238.52	$238.50	$238.50
Purchase #7	$106.55	7.241%	$114.2653	$114.27	$114.25	$114.30
7 purchase totals =	$1,026.85		$1,106.4031	$1,106.40	$1,106.40	$1,106.40