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	$213.45	4.665%	$223.4074	$223.41	$223.40	$223.40
Purchase #2	$191.69	3.554%	$198.5027	$198.50	$198.50	$198.50
Purchase #3	$67.72	4.691%	$70.8967	$70.90	$70.90	$70.90
Purchase #4	$139.27	4.760%	$145.8993	$145.90	$145.90	$145.90
Purchase #5	$95.28	12.198%	$106.9023	$106.90	$106.90	$106.90
Purchase #6	$93.91	5.716%	$99.2779	$99.28	$99.30	$99.30
Purchase #7	$200.27	9.827%	$219.9505	$219.95	$219.95	$220.00
7 purchase totals =	$1,001.59		$1,064.8368	$1,064.84	$1,064.85	$1,064.90