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	$186.82	3.212%	$192.8207	$192.82	$192.80	$192.80
Purchase #2	$81.54	4.654%	$85.3349	$85.33	$85.35	$85.30
Purchase #3	$50.58	11.206%	$56.248	$56.25	$56.25	$56.20
Purchase #4	$52.97	6.298%	$56.3061	$56.31	$56.30	$56.30
Purchase #5	$92.28	8.209%	$99.8553	$99.86	$99.85	$99.90
Purchase #6	$103.57	10.760%	$114.7141	$114.71	$114.70	$114.70
Purchase #7	$85.56	13.394%	$97.0199	$97.02	$97.00	$97.00
7 purchase totals =	$653.32		$702.2990	$702.30	$702.25	$702.20