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	$98.26	3.256%	$101.4593	$101.46	$101.45	$101.50
Purchase #2	$37.74	4.105%	$39.2892	$39.29	$39.30	$39.30
Purchase #3	$48.52	10.222%	$53.4797	$53.48	$53.50	$53.50
Purchase #4	$186.88	12.641%	$210.5035	$210.50	$210.50	$210.50
Purchase #5	$50.36	5.800%	$53.2809	$53.28	$53.30	$53.30
Purchase #6	$250.66	4.723%	$262.4987	$262.50	$262.50	$262.50
Purchase #7	$209.30	10.472%	$231.2179	$231.22	$231.20	$231.20
7 purchase totals =	$881.72		$951.7292	$951.73	$951.75	$951.80