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	$189.26	3.608%	$196.0885	$196.09	$196.10	$196.10
Purchase #2	$185.73	8.534%	$201.5802	$201.58	$201.60	$201.60
Purchase #3	$140.41	11.314%	$156.296	$156.30	$156.30	$156.30
Purchase #4	$171.51	9.473%	$187.7571	$187.76	$187.75	$187.80
Purchase #5	$172.64	4.389%	$180.2172	$180.22	$180.20	$180.20
Purchase #6	$168.95	13.680%	$192.0624	$192.06	$192.05	$192.10
Purchase #7	$100.82	10.667%	$111.5745	$111.57	$111.55	$111.60
7 purchase totals =	$1,129.32		$1,225.5759	$1,225.58	$1,225.55	$1,225.70