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	$149.84	8.498%	$162.5734	$162.57	$162.55	$162.60
Purchase #2	$155.50	11.178%	$172.8818	$172.88	$172.90	$172.90
Purchase #3	$216.31	13.450%	$245.4037	$245.40	$245.40	$245.40
Purchase #4	$212.75	13.637%	$241.7627	$241.76	$241.75	$241.80
Purchase #5	$41.87	8.114%	$45.2673	$45.27	$45.25	$45.30
Purchase #6	$24.56	12.592%	$27.6526	$27.65	$27.65	$27.70
Purchase #7	$175.52	8.756%	$190.8885	$190.89	$190.90	$190.90
7 purchase totals =	$976.35		$1,086.4300	$1,086.42	$1,086.40	$1,086.60