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	$55.95	9.616%	$61.3302	$61.33	$61.35	$61.30
Purchase #2	$193.74	10.148%	$213.4007	$213.40	$213.40	$213.40
Purchase #3	$107.64	3.185%	$111.0683	$111.07	$111.05	$111.10
Purchase #4	$181.77	3.135%	$187.4685	$187.47	$187.45	$187.50
Purchase #5	$150.84	5.232%	$158.7319	$158.73	$158.75	$158.70
Purchase #6	$207.75	7.130%	$222.5626	$222.56	$222.55	$222.60
Purchase #7	$9.89	5.744%	$10.4581	$10.46	$10.45	$10.50
7 purchase totals =	$907.58		$965.0203	$965.02	$965.00	$965.10