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	$250.56	4.188%	$261.0535	$261.05	$261.05	$261.10
Purchase #2	$160.59	3.123%	$165.6052	$165.61	$165.60	$165.60
Purchase #3	$183.27	9.394%	$200.4864	$200.49	$200.50	$200.50
Purchase #4	$36.49	13.616%	$41.4585	$41.46	$41.45	$41.50
Purchase #5	$136.93	11.450%	$152.6085	$152.61	$152.60	$152.60
Purchase #6	$200.96	8.501%	$218.0436	$218.04	$218.05	$218.00
Purchase #7	$157.32	5.663%	$166.229	$166.23	$166.25	$166.20
7 purchase totals =	$1,126.12		$1,205.4847	$1,205.49	$1,205.50	$1,205.50