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	$216.64	4.494%	$226.3758	$226.38	$226.40	$226.40
Purchase #2	$65.59	12.131%	$73.5467	$73.55	$73.55	$73.50
Purchase #3	$94.48	5.250%	$99.4402	$99.44	$99.45	$99.40
Purchase #4	$166.70	3.633%	$172.7562	$172.76	$172.75	$172.80
Purchase #5	$229.89	9.112%	$250.8376	$250.84	$250.85	$250.80
Purchase #6	$121.32	8.320%	$131.4138	$131.41	$131.40	$131.40
Purchase #7	$172.90	11.209%	$192.2804	$192.28	$192.30	$192.30
7 purchase totals =	$1,067.52		$1,146.6507	$1,146.66	$1,146.70	$1,146.60