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	$168.46	6.586%	$179.5548	$179.55	$179.55	$179.60
Purchase #2	$24.28	5.369%	$25.5836	$25.58	$25.60	$25.60
Purchase #3	$110.59	6.628%	$117.9199	$117.92	$117.90	$117.90
Purchase #4	$239.89	7.246%	$257.2724	$257.27	$257.25	$257.30
Purchase #5	$198.86	3.242%	$205.307	$205.31	$205.30	$205.30
Purchase #6	$183.34	7.170%	$196.4855	$196.49	$196.50	$196.50
Purchase #7	$135.34	11.498%	$150.9014	$150.90	$150.90	$150.90
7 purchase totals =	$1,060.76		$1,133.0246	$1,133.02	$1,133.00	$1,133.10