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	$228.94	7.784%	$246.7607	$246.76	$246.75	$246.80
Purchase #2	$165.25	6.732%	$176.3746	$176.37	$176.35	$176.40
Purchase #3	$145.65	7.566%	$156.6699	$156.67	$156.65	$156.70
Purchase #4	$35.55	3.290%	$36.7196	$36.72	$36.70	$36.70
Purchase #5	$187.67	6.307%	$199.5063	$199.51	$199.50	$199.50
Purchase #6	$153.52	11.546%	$171.2454	$171.25	$171.25	$171.20
Purchase #7	$164.58	12.606%	$185.327	$185.33	$185.35	$185.30
7 purchase totals =	$1,081.16		$1,172.6035	$1,172.61	$1,172.55	$1,172.60