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	$94.40	6.524%	$100.5587	$100.56	$100.55	$100.60
Purchase #2	$186.40	5.460%	$196.5774	$196.58	$196.60	$196.60
Purchase #3	$112.92	11.837%	$126.2863	$126.29	$126.30	$126.30
Purchase #4	$158.99	4.171%	$165.6215	$165.62	$165.60	$165.60
Purchase #5	$110.35	4.490%	$115.3047	$115.30	$115.30	$115.30
Purchase #6	$197.89	12.127%	$221.8881	$221.89	$221.90	$221.90
Purchase #7	$183.77	9.212%	$200.6989	$200.70	$200.70	$200.70
7 purchase totals =	$1,044.72		$1,126.9356	$1,126.94	$1,126.95	$1,127.00