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	$182.70	6.687%	$194.9171	$194.92	$194.90	$194.90
Purchase #2	$152.49	9.515%	$166.9994	$167.00	$167.00	$167.00
Purchase #3	$188.62	13.847%	$214.7382	$214.74	$214.75	$214.70
Purchase #4	$213.89	5.157%	$224.9203	$224.92	$224.90	$224.90
Purchase #5	$223.57	4.490%	$233.6083	$233.61	$233.60	$233.60
Purchase #6	$18.29	10.810%	$20.2671	$20.27	$20.25	$20.30
Purchase #7	$36.61	10.359%	$40.4024	$40.40	$40.40	$40.40
7 purchase totals =	$1,016.17		$1,095.8528	$1,095.86	$1,095.80	$1,095.80