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	$174.89	12.284%	$196.3735	$196.37	$196.35	$196.40
Purchase #2	$33.58	4.474%	$35.0824	$35.08	$35.10	$35.10
Purchase #3	$53.49	11.394%	$59.5847	$59.58	$59.60	$59.60
Purchase #4	$197.75	12.379%	$222.2295	$222.23	$222.25	$222.20
Purchase #5	$64.89	6.379%	$69.0293	$69.03	$69.05	$69.00
Purchase #6	$228.45	3.298%	$235.9843	$235.98	$236.00	$236.00
Purchase #7	$190.66	7.136%	$204.2655	$204.27	$204.25	$204.30
7 purchase totals =	$943.71		$1,022.5492	$1,022.54	$1,022.60	$1,022.60