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	$98.40	13.739%	$111.9192	$111.92	$111.90	$111.90
Purchase #2	$161.45	13.431%	$183.1343	$183.13	$183.15	$183.10
Purchase #3	$131.65	8.594%	$142.964	$142.96	$142.95	$143.00
Purchase #4	$191.40	8.303%	$207.2919	$207.29	$207.30	$207.30
Purchase #5	$202.75	13.229%	$229.5718	$229.57	$229.55	$229.60
Purchase #6	$151.76	9.391%	$166.0118	$166.01	$166.00	$166.00
Purchase #7	$119.33	6.742%	$127.3752	$127.38	$127.40	$127.40
7 purchase totals =	$1,056.74		$1,168.2682	$1,168.26	$1,168.25	$1,168.30