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	$187.63	3.723%	$194.6155	$194.62	$194.60	$194.60
Purchase #2	$54.58	12.390%	$61.3425	$61.34	$61.35	$61.30
Purchase #3	$213.86	6.380%	$227.5043	$227.50	$227.50	$227.50
Purchase #4	$22.65	5.517%	$23.8996	$23.90	$23.90	$23.90
Purchase #5	$30.53	9.603%	$33.4618	$33.46	$33.45	$33.50
Purchase #6	$96.46	10.600%	$106.6848	$106.68	$106.70	$106.70
Purchase #7	$55.76	6.531%	$59.4017	$59.40	$59.40	$59.40
7 purchase totals =	$661.47		$706.9102	$706.90	$706.90	$706.90