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	$92.86	9.230%	$101.431	$101.43	$101.45	$101.40
Purchase #2	$87.32	3.809%	$90.646	$90.65	$90.65	$90.60
Purchase #3	$246.89	6.712%	$263.4613	$263.46	$263.45	$263.50
Purchase #4	$137.37	12.138%	$154.044	$154.04	$154.05	$154.00
Purchase #5	$82.77	7.687%	$89.1325	$89.13	$89.15	$89.10
Purchase #6	$238.41	6.769%	$254.548	$254.55	$254.55	$254.50
Purchase #7	$193.62	10.815%	$214.56	$214.56	$214.55	$214.60
7 purchase totals =	$1,079.24		$1,167.8228	$1,167.82	$1,167.85	$1,167.70