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	$174.88	13.132%	$197.8452	$197.85	$197.85	$197.80
Purchase #2	$152.87	10.206%	$168.4719	$168.47	$168.45	$168.50
Purchase #3	$144.54	9.701%	$158.5618	$158.56	$158.55	$158.60
Purchase #4	$160.66	12.411%	$180.5995	$180.60	$180.60	$180.60
Purchase #5	$153.79	11.383%	$171.2959	$171.30	$171.30	$171.30
Purchase #6	$88.74	11.739%	$99.1572	$99.16	$99.15	$99.20
Purchase #7	$53.66	10.569%	$59.3313	$59.33	$59.35	$59.30
7 purchase totals =	$929.14		$1,035.2628	$1,035.27	$1,035.25	$1,035.30