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	$182.77	7.516%	$196.507	$196.51	$196.50	$196.50
Purchase #2	$199.47	9.173%	$217.7674	$217.77	$217.75	$217.80
Purchase #3	$149.62	12.354%	$168.1041	$168.10	$168.10	$168.10
Purchase #4	$205.83	12.360%	$231.2706	$231.27	$231.25	$231.30
Purchase #5	$123.91	5.317%	$130.4983	$130.50	$130.50	$130.50
Purchase #6	$80.80	7.690%	$87.0135	$87.01	$87.00	$87.00
Purchase #7	$151.43	6.104%	$160.6733	$160.67	$160.65	$160.70
7 purchase totals =	$1,093.83		$1,191.8342	$1,191.83	$1,191.75	$1,191.90