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	$198.74	9.344%	$217.3103	$217.31	$217.30	$217.30
Purchase #2	$82.86	9.290%	$90.5577	$90.56	$90.55	$90.60
Purchase #3	$219.77	10.480%	$242.8019	$242.80	$242.80	$242.80
Purchase #4	$82.77	8.385%	$89.7103	$89.71	$89.70	$89.70
Purchase #5	$102.61	3.874%	$106.5851	$106.59	$106.60	$106.60
Purchase #6	$137.36	3.350%	$141.9616	$141.96	$141.95	$142.00
Purchase #7	$156.96	9.403%	$171.7189	$171.72	$171.70	$171.70
7 purchase totals =	$981.07		$1,060.6458	$1,060.65	$1,060.60	$1,060.70