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	$165.53	5.188%	$174.1177	$174.12	$174.10	$174.10
Purchase #2	$89.55	8.279%	$96.9638	$96.96	$96.95	$97.00
Purchase #3	$194.75	11.713%	$217.5611	$217.56	$217.55	$217.60
Purchase #4	$37.43	8.707%	$40.689	$40.69	$40.70	$40.70
Purchase #5	$114.91	10.606%	$127.0974	$127.10	$127.10	$127.10
Purchase #6	$27.28	7.852%	$29.422	$29.42	$29.40	$29.40
Purchase #7	$155.38	7.642%	$167.2541	$167.25	$167.25	$167.30
7 purchase totals =	$784.83		$853.1051	$853.10	$853.05	$853.20