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	$194.46	6.478%	$207.0571	$207.06	$207.05	$207.10
Purchase #2	$202.94	7.353%	$217.8622	$217.86	$217.85	$217.90
Purchase #3	$105.48	5.653%	$111.4428	$111.44	$111.45	$111.40
Purchase #4	$149.36	12.179%	$167.5506	$167.55	$167.55	$167.60
Purchase #5	$59.29	11.177%	$65.9168	$65.92	$65.90	$65.90
Purchase #6	$201.86	5.180%	$212.3163	$212.32	$212.30	$212.30
Purchase #7	$142.83	5.827%	$151.1527	$151.15	$151.15	$151.20
7 purchase totals =	$1,056.22		$1,133.2985	$1,133.30	$1,133.25	$1,133.40