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	$219.64	7.631%	$236.4007	$236.40	$236.40	$236.40
Purchase #2	$162.34	7.520%	$174.548	$174.55	$174.55	$174.50
Purchase #3	$112.76	13.825%	$128.3491	$128.35	$128.35	$128.30
Purchase #4	$106.98	6.856%	$114.3145	$114.31	$114.30	$114.30
Purchase #5	$71.87	13.624%	$81.6616	$81.66	$81.65	$81.70
Purchase #6	$249.84	13.853%	$284.4503	$284.45	$284.45	$284.50
Purchase #7	$40.39	3.222%	$41.6914	$41.69	$41.70	$41.70
7 purchase totals =	$963.82		$1,061.4156	$1,061.41	$1,061.40	$1,061.40