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	$192.83	10.303%	$212.6973	$212.70	$212.70	$212.70
Purchase #2	$55.36	7.331%	$59.4184	$59.42	$59.40	$59.40
Purchase #3	$67.59	4.370%	$70.5437	$70.54	$70.55	$70.50
Purchase #4	$205.79	10.544%	$227.4885	$227.49	$227.50	$227.50
Purchase #5	$100.98	8.164%	$109.224	$109.22	$109.20	$109.20
Purchase #6	$170.94	12.203%	$191.7998	$191.80	$191.80	$191.80
Purchase #7	$244.84	8.436%	$265.4947	$265.49	$265.50	$265.50
7 purchase totals =	$1,038.33		$1,136.6664	$1,136.66	$1,136.65	$1,136.60