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	$245.77	7.713%	$264.7262	$264.73	$264.75	$264.70
Purchase #2	$6.45	4.769%	$6.7576	$6.76	$6.75	$6.80
Purchase #3	$172.69	6.514%	$183.939	$183.94	$183.95	$183.90
Purchase #4	$42.60	6.656%	$45.4355	$45.44	$45.45	$45.40
Purchase #5	$247.39	5.489%	$260.9692	$260.97	$260.95	$261.00
Purchase #6	$117.27	11.764%	$131.0656	$131.07	$131.05	$131.10
Purchase #7	$205.66	6.204%	$218.4191	$218.42	$218.40	$218.40
7 purchase totals =	$1,037.83		$1,111.3122	$1,111.33	$1,111.30	$1,111.30