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	$213.54	4.503%	$223.1557	$223.16	$223.15	$223.20
Purchase #2	$182.39	9.864%	$200.3809	$200.38	$200.40	$200.40
Purchase #3	$39.94	4.180%	$41.6095	$41.61	$41.60	$41.60
Purchase #4	$183.73	5.823%	$194.4286	$194.43	$194.45	$194.40
Purchase #5	$143.88	5.373%	$151.6107	$151.61	$151.60	$151.60
Purchase #6	$92.93	12.277%	$104.339	$104.34	$104.35	$104.30
Purchase #7	$245.39	10.727%	$271.713	$271.71	$271.70	$271.70
7 purchase totals =	$1,101.80		$1,187.2374	$1,187.24	$1,187.25	$1,187.20