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	$176.46	11.178%	$196.1847	$196.18	$196.20	$196.20
Purchase #2	$66.83	8.121%	$72.2573	$72.26	$72.25	$72.30
Purchase #3	$54.65	12.340%	$61.3938	$61.39	$61.40	$61.40
Purchase #4	$227.36	5.346%	$239.5147	$239.51	$239.50	$239.50
Purchase #5	$198.37	10.315%	$218.8319	$218.83	$218.85	$218.80
Purchase #6	$23.27	11.336%	$25.9079	$25.91	$25.90	$25.90
Purchase #7	$234.39	9.374%	$256.3617	$256.36	$256.35	$256.40
7 purchase totals =	$981.33		$1,070.4520	$1,070.44	$1,070.45	$1,070.50