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	$181.35	8.426%	$196.6306	$196.63	$196.65	$196.60
Purchase #2	$239.50	6.868%	$255.9489	$255.95	$255.95	$255.90
Purchase #3	$39.85	7.494%	$42.8364	$42.84	$42.85	$42.80
Purchase #4	$152.46	4.522%	$159.3542	$159.35	$159.35	$159.40
Purchase #5	$191.84	6.690%	$204.6741	$204.67	$204.65	$204.70
Purchase #6	$18.54	12.710%	$20.8964	$20.90	$20.90	$20.90
Purchase #7	$162.29	7.597%	$174.6192	$174.62	$174.60	$174.60
7 purchase totals =	$985.83		$1,054.9598	$1,054.96	$1,054.95	$1,054.90