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	$182.58	6.553%	$194.5445	$194.54	$194.55	$194.50
Purchase #2	$136.97	3.151%	$141.2859	$141.29	$141.30	$141.30
Purchase #3	$61.35	11.500%	$68.4053	$68.41	$68.40	$68.40
Purchase #4	$90.39	8.696%	$98.2503	$98.25	$98.25	$98.30
Purchase #5	$123.93	10.725%	$137.2215	$137.22	$137.20	$137.20
Purchase #6	$162.56	7.146%	$174.1765	$174.18	$174.20	$174.20
Purchase #7	$247.31	11.425%	$275.5652	$275.57	$275.55	$275.60
7 purchase totals =	$1,005.09		$1,089.4492	$1,089.46	$1,089.45	$1,089.50