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	$167.90	3.719%	$174.1442	$174.14	$174.15	$174.10
Purchase #2	$7.65	8.840%	$8.3263	$8.33	$8.35	$8.30
Purchase #3	$87.69	5.388%	$92.4147	$92.41	$92.40	$92.40
Purchase #4	$230.63	5.188%	$242.5951	$242.60	$242.60	$242.60
Purchase #5	$100.71	13.663%	$114.47	$114.47	$114.45	$114.50
Purchase #6	$77.44	6.441%	$82.4279	$82.43	$82.45	$82.40
Purchase #7	$249.87	5.564%	$263.7728	$263.77	$263.75	$263.80
7 purchase totals =	$921.89		$978.1510	$978.15	$978.15	$978.10