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	$213.39	7.109%	$228.5599	$228.56	$228.55	$228.60
Purchase #2	$105.63	8.165%	$114.2547	$114.25	$114.25	$114.30
Purchase #3	$233.29	7.107%	$249.8699	$249.87	$249.85	$249.90
Purchase #4	$189.91	11.242%	$211.2597	$211.26	$211.25	$211.30
Purchase #5	$112.93	10.485%	$124.7707	$124.77	$124.75	$124.80
Purchase #6	$59.78	12.176%	$67.0588	$67.06	$67.05	$67.10
Purchase #7	$34.29	8.121%	$37.0747	$37.07	$37.05	$37.10
7 purchase totals =	$949.22		$1,032.8484	$1,032.84	$1,032.75	$1,033.10