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	$98.93	12.281%	$111.0796	$111.08	$111.10	$111.10
Purchase #2	$121.30	3.618%	$125.6886	$125.69	$125.70	$125.70
Purchase #3	$165.56	6.655%	$176.578	$176.58	$176.60	$176.60
Purchase #4	$152.62	6.437%	$162.4441	$162.44	$162.45	$162.40
Purchase #5	$221.77	3.139%	$228.7314	$228.73	$228.75	$228.70
Purchase #6	$128.65	4.830%	$134.8638	$134.86	$134.85	$134.90
Purchase #7	$155.43	6.715%	$165.8671	$165.87	$165.85	$165.90
7 purchase totals =	$1,044.26		$1,105.2526	$1,105.25	$1,105.30	$1,105.30