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	$132.73	13.259%	$150.3287	$150.33	$150.35	$150.30
Purchase #2	$222.32	4.795%	$232.9802	$232.98	$233.00	$233.00
Purchase #3	$9.39	12.830%	$10.5947	$10.59	$10.60	$10.60
Purchase #4	$150.61	3.151%	$155.3557	$155.36	$155.35	$155.40
Purchase #5	$208.35	6.647%	$222.199	$222.20	$222.20	$222.20
Purchase #6	$166.63	10.617%	$184.3211	$184.32	$184.30	$184.30
Purchase #7	$141.57	7.269%	$151.8607	$151.86	$151.85	$151.90
7 purchase totals =	$1,031.60		$1,107.6401	$1,107.64	$1,107.65	$1,107.70