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	$190.87	4.300%	$199.0774	$199.08	$199.10	$199.10
Purchase #2	$59.60	5.114%	$62.6479	$62.65	$62.65	$62.60
Purchase #3	$67.89	10.608%	$75.0918	$75.09	$75.10	$75.10
Purchase #4	$204.54	3.651%	$212.0078	$212.01	$212.00	$212.00
Purchase #5	$95.51	9.298%	$104.3905	$104.39	$104.40	$104.40
Purchase #6	$240.73	9.435%	$263.4429	$263.44	$263.45	$263.40
Purchase #7	$220.69	5.837%	$233.5717	$233.57	$233.55	$233.60
7 purchase totals =	$1,079.83		$1,150.2300	$1,150.23	$1,150.25	$1,150.20