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	$64.42	7.190%	$69.0518	$69.05	$69.05	$69.10
Purchase #2	$245.47	4.651%	$256.8868	$256.89	$256.90	$256.90
Purchase #3	$242.83	4.826%	$254.549	$254.55	$254.55	$254.50
Purchase #4	$91.94	6.869%	$98.2554	$98.26	$98.25	$98.30
Purchase #5	$137.75	6.344%	$146.4889	$146.49	$146.50	$146.50
Purchase #6	$110.45	7.181%	$118.3814	$118.38	$118.40	$118.40
Purchase #7	$228.92	11.222%	$254.6094	$254.61	$254.60	$254.60
7 purchase totals =	$1,121.78		$1,198.2227	$1,198.23	$1,198.25	$1,198.30