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	$162.77	10.229%	$179.4197	$179.42	$179.40	$179.40
Purchase #2	$156.60	5.454%	$165.141	$165.14	$165.15	$165.10
Purchase #3	$62.83	12.206%	$70.499	$70.50	$70.50	$70.50
Purchase #4	$20.27	10.163%	$22.33	$22.33	$22.35	$22.30
Purchase #5	$138.87	12.445%	$156.1524	$156.15	$156.15	$156.20
Purchase #6	$186.43	11.570%	$208	$208.00	$208.00	$208.00
Purchase #7	$241.56	8.406%	$261.8655	$261.87	$261.85	$261.90
7 purchase totals =	$969.33		$1,063.4076	$1,063.41	$1,063.40	$1,063.40