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	$95.66	11.590%	$106.747	$106.75	$106.75	$106.70
Purchase #2	$33.89	10.151%	$37.3302	$37.33	$37.35	$37.30
Purchase #3	$39.89	6.535%	$42.4968	$42.50	$42.50	$42.50
Purchase #4	$211.28	5.114%	$222.0849	$222.08	$222.10	$222.10
Purchase #5	$157.26	3.194%	$162.2829	$162.28	$162.30	$162.30
Purchase #6	$178.75	4.331%	$186.4917	$186.49	$186.50	$186.50
Purchase #7	$231.51	5.635%	$244.5556	$244.56	$244.55	$244.60
7 purchase totals =	$948.24		$1,001.9891	$1,001.99	$1,002.05	$1,002.00