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	$196.25	6.765%	$209.5263	$209.53	$209.55	$209.50
Purchase #2	$41.87	11.126%	$46.5285	$46.53	$46.55	$46.50
Purchase #3	$37.36	12.449%	$42.0109	$42.01	$42.00	$42.00
Purchase #4	$151.59	12.329%	$170.2795	$170.28	$170.30	$170.30
Purchase #5	$234.31	8.603%	$254.4677	$254.47	$254.45	$254.50
Purchase #6	$156.82	7.508%	$168.594	$168.59	$168.60	$168.60
Purchase #7	$149.63	7.255%	$160.4857	$160.49	$160.50	$160.50
7 purchase totals =	$967.83		$1,051.8926	$1,051.90	$1,051.95	$1,051.90