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	$181.48	7.286%	$194.7026	$194.70	$194.70	$194.70
Purchase #2	$17.54	11.302%	$19.5224	$19.52	$19.50	$19.50
Purchase #3	$238.52	4.528%	$249.3202	$249.32	$249.30	$249.30
Purchase #4	$182.50	5.445%	$192.4371	$192.44	$192.45	$192.40
Purchase #5	$168.31	5.814%	$178.0955	$178.10	$178.10	$178.10
Purchase #6	$172.72	8.143%	$186.7846	$186.78	$186.80	$186.80
Purchase #7	$55.63	7.742%	$59.9369	$59.94	$59.95	$59.90
7 purchase totals =	$1,016.70		$1,080.7993	$1,080.80	$1,080.80	$1,080.70