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	$196.33	6.591%	$209.2701	$209.27	$209.25	$209.30
Purchase #2	$189.59	10.400%	$209.3074	$209.31	$209.30	$209.30
Purchase #3	$190.37	5.367%	$200.5872	$200.59	$200.60	$200.60
Purchase #4	$44.65	3.474%	$46.2011	$46.20	$46.20	$46.20
Purchase #5	$234.77	4.864%	$246.1892	$246.19	$246.20	$246.20
Purchase #6	$155.40	4.682%	$162.6758	$162.68	$162.70	$162.70
Purchase #7	$32.89	7.265%	$35.2795	$35.28	$35.30	$35.30
7 purchase totals =	$1,044.00		$1,109.5103	$1,109.52	$1,109.55	$1,109.60