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	$211.52	13.520%	$240.1175	$240.12	$240.10	$240.10
Purchase #2	$184.54	13.242%	$208.9768	$208.98	$209.00	$209.00
Purchase #3	$151.40	10.762%	$167.6937	$167.69	$167.70	$167.70
Purchase #4	$95.61	10.821%	$105.956	$105.96	$105.95	$106.00
Purchase #5	$115.57	10.645%	$127.8724	$127.87	$127.85	$127.90
Purchase #6	$172.59	5.796%	$182.5933	$182.59	$182.60	$182.60
Purchase #7	$242.33	10.783%	$268.4604	$268.46	$268.45	$268.50
7 purchase totals =	$1,173.56		$1,301.6701	$1,301.67	$1,301.65	$1,301.80