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	$181.54	3.687%	$188.2334	$188.23	$188.25	$188.20
Purchase #2	$11.51	8.489%	$12.4871	$12.49	$12.50	$12.50
Purchase #3	$162.40	4.406%	$169.5553	$169.56	$169.55	$169.60
Purchase #4	$221.28	6.835%	$236.4045	$236.40	$236.40	$236.40
Purchase #5	$198.27	11.768%	$221.6024	$221.60	$221.60	$221.60
Purchase #6	$84.63	12.147%	$94.91	$94.91	$94.90	$94.90
Purchase #7	$111.63	10.781%	$123.6648	$123.66	$123.65	$123.70
7 purchase totals =	$971.26		$1,046.8575	$1,046.85	$1,046.85	$1,046.90