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	$59.47	8.183%	$64.3364	$64.34	$64.35	$64.30
Purchase #2	$159.28	4.465%	$166.3919	$166.39	$166.40	$166.40
Purchase #3	$134.67	7.477%	$144.7393	$144.74	$144.75	$144.70
Purchase #4	$91.29	4.162%	$95.0895	$95.09	$95.10	$95.10
Purchase #5	$117.92	11.449%	$131.4207	$131.42	$131.40	$131.40
Purchase #6	$184.88	8.517%	$200.6262	$200.63	$200.65	$200.60
Purchase #7	$196.66	7.745%	$211.8913	$211.89	$211.90	$211.90
7 purchase totals =	$944.17		$1,014.4953	$1,014.50	$1,014.55	$1,014.40