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	$181.37	8.127%	$196.1099	$196.11	$196.10	$196.10
Purchase #2	$235.42	11.335%	$262.1049	$262.10	$262.10	$262.10
Purchase #3	$96.75	4.201%	$100.8145	$100.81	$100.80	$100.80
Purchase #4	$114.76	11.764%	$128.2604	$128.26	$128.25	$128.30
Purchase #5	$152.99	9.668%	$167.7811	$167.78	$167.80	$167.80
Purchase #6	$73.78	11.147%	$82.0043	$82.00	$82.00	$82.00
Purchase #7	$88.62	9.245%	$96.8129	$96.81	$96.80	$96.80
7 purchase totals =	$943.69		$1,033.8880	$1,033.87	$1,033.85	$1,033.90