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	$184.95	11.203%	$205.6699	$205.67	$205.65	$205.70
Purchase #2	$146.46	4.138%	$152.5205	$152.52	$152.50	$152.50
Purchase #3	$137.94	11.562%	$153.8886	$153.89	$153.90	$153.90
Purchase #4	$73.68	11.467%	$82.1289	$82.13	$82.15	$82.10
Purchase #5	$97.25	13.325%	$110.2086	$110.21	$110.20	$110.20
Purchase #6	$127.43	9.403%	$139.4122	$139.41	$139.40	$139.40
Purchase #7	$226.53	9.370%	$247.7559	$247.76	$247.75	$247.80
7 purchase totals =	$994.24		$1,091.5846	$1,091.59	$1,091.55	$1,091.60