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	$174.50	12.345%	$196.042	$196.04	$196.05	$196.00
Purchase #2	$6.96	4.830%	$7.2962	$7.30	$7.30	$7.30
Purchase #3	$63.36	11.773%	$70.8194	$70.82	$70.80	$70.80
Purchase #4	$73.69	6.656%	$78.5948	$78.59	$78.60	$78.60
Purchase #5	$93.91	6.660%	$100.1644	$100.16	$100.15	$100.20
Purchase #6	$215.39	13.466%	$244.3944	$244.39	$244.40	$244.40
Purchase #7	$151.48	7.260%	$162.4774	$162.48	$162.50	$162.50
7 purchase totals =	$779.29		$859.7886	$859.78	$859.80	$859.80