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	$228.62	3.542%	$236.7177	$236.72	$236.70	$236.70
Purchase #2	$208.56	10.524%	$230.5089	$230.51	$230.50	$230.50
Purchase #3	$48.26	5.581%	$50.9534	$50.95	$50.95	$51.00
Purchase #4	$73.87	6.705%	$78.823	$78.82	$78.80	$78.80
Purchase #5	$198.64	10.513%	$219.523	$219.52	$219.50	$219.50
Purchase #6	$178.51	4.130%	$185.8825	$185.88	$185.90	$185.90
Purchase #7	$96.35	3.655%	$99.8716	$99.87	$99.85	$99.90
7 purchase totals =	$1,032.81		$1,102.2801	$1,102.27	$1,102.20	$1,102.30