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	$214.27	7.177%	$229.6482	$229.65	$229.65	$229.60
Purchase #2	$142.99	4.354%	$149.2158	$149.22	$149.20	$149.20
Purchase #3	$185.78	7.815%	$200.2987	$200.30	$200.30	$200.30
Purchase #4	$68.47	6.474%	$72.9027	$72.90	$72.90	$72.90
Purchase #5	$86.55	9.443%	$94.7229	$94.72	$94.70	$94.70
Purchase #6	$183.51	7.242%	$196.7998	$196.80	$196.80	$196.80
Purchase #7	$98.69	10.457%	$109.01	$109.01	$109.00	$109.00
7 purchase totals =	$980.26		$1,052.5981	$1,052.60	$1,052.55	$1,052.50