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	$192.75	6.177%	$204.6562	$204.66	$204.65	$204.70
Purchase #2	$186.48	5.514%	$196.7625	$196.76	$196.75	$196.80
Purchase #3	$105.35	7.568%	$113.3229	$113.32	$113.30	$113.30
Purchase #4	$127.89	13.483%	$145.1334	$145.13	$145.15	$145.10
Purchase #5	$180.32	8.852%	$196.2819	$196.28	$196.30	$196.30
Purchase #6	$155.90	5.211%	$164.0239	$164.02	$164.00	$164.00
Purchase #7	$190.85	4.545%	$199.5241	$199.52	$199.50	$199.50
7 purchase totals =	$1,139.54		$1,219.7049	$1,219.69	$1,219.65	$1,219.70