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	$102.53	11.739%	$114.566	$114.57	$114.55	$114.60
Purchase #2	$162.91	10.306%	$179.6995	$179.70	$179.70	$179.70
Purchase #3	$16.44	13.152%	$18.6022	$18.60	$18.60	$18.60
Purchase #4	$50.74	7.800%	$54.6977	$54.70	$54.70	$54.70
Purchase #5	$173.93	4.230%	$181.2872	$181.29	$181.30	$181.30
Purchase #6	$244.63	10.861%	$271.1993	$271.20	$271.20	$271.20
Purchase #7	$180.27	5.584%	$190.3363	$190.34	$190.35	$190.30
7 purchase totals =	$931.45		$1,010.3882	$1,010.40	$1,010.40	$1,010.40