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	$212.73	4.489%	$222.2794	$222.28	$222.30	$222.30
Purchase #2	$209.44	4.528%	$218.9234	$218.92	$218.90	$218.90
Purchase #3	$128.98	5.365%	$135.8998	$135.90	$135.90	$135.90
Purchase #4	$195.92	4.701%	$205.1302	$205.13	$205.15	$205.10
Purchase #5	$100.97	4.502%	$105.5157	$105.52	$105.50	$105.50
Purchase #6	$146.57	6.481%	$156.0692	$156.07	$156.05	$156.10
Purchase #7	$38.61	13.320%	$43.7529	$43.75	$43.75	$43.80
7 purchase totals =	$1,033.22		$1,087.5706	$1,087.57	$1,087.55	$1,087.60