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	$156.98	6.430%	$167.0738	$167.07	$167.05	$167.10
Purchase #2	$11.27	13.795%	$12.8247	$12.82	$12.80	$12.80
Purchase #3	$122.42	4.531%	$127.9669	$127.97	$127.95	$128.00
Purchase #4	$53.74	10.503%	$59.3843	$59.38	$59.40	$59.40
Purchase #5	$170.49	11.193%	$189.5729	$189.57	$189.55	$189.60
Purchase #6	$170.92	13.477%	$193.9549	$193.95	$193.95	$194.00
Purchase #7	$181.58	8.110%	$196.3061	$196.31	$196.30	$196.30
7 purchase totals =	$867.40		$947.0836	$947.07	$947.00	$947.20