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	$40.72	8.863%	$44.329	$44.33	$44.35	$44.30
Purchase #2	$227.88	6.731%	$243.2186	$243.22	$243.20	$243.20
Purchase #3	$103.80	5.339%	$109.3419	$109.34	$109.35	$109.30
Purchase #4	$91.36	11.358%	$101.7367	$101.74	$101.75	$101.70
Purchase #5	$249.77	5.103%	$262.5158	$262.52	$262.50	$262.50
Purchase #6	$58.87	3.870%	$61.1483	$61.15	$61.15	$61.10
Purchase #7	$241.36	3.634%	$250.131	$250.13	$250.15	$250.10
7 purchase totals =	$1,013.76		$1,072.4213	$1,072.43	$1,072.45	$1,072.20