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	$206.81	4.125%	$215.3409	$215.34	$215.35	$215.30
Purchase #2	$53.83	4.393%	$56.1948	$56.19	$56.20	$56.20
Purchase #3	$249.71	5.874%	$264.378	$264.38	$264.40	$264.40
Purchase #4	$62.54	3.309%	$64.6094	$64.61	$64.60	$64.60
Purchase #5	$193.58	3.477%	$200.3108	$200.31	$200.30	$200.30
Purchase #6	$49.38	13.468%	$56.0305	$56.03	$56.05	$56.00
Purchase #7	$152.64	3.561%	$158.0755	$158.08	$158.10	$158.10
7 purchase totals =	$968.49		$1,014.9399	$1,014.94	$1,015.00	$1,014.90