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	$218.79	8.482%	$237.3478	$237.35	$237.35	$237.30
Purchase #2	$42.55	6.557%	$45.34	$45.34	$45.35	$45.30
Purchase #3	$108.55	8.769%	$118.0687	$118.07	$118.05	$118.10
Purchase #4	$204.83	3.413%	$211.8208	$211.82	$211.80	$211.80
Purchase #5	$168.85	10.403%	$186.4155	$186.42	$186.40	$186.40
Purchase #6	$65.39	3.166%	$67.4602	$67.46	$67.45	$67.50
Purchase #7	$96.77	9.305%	$105.7744	$105.77	$105.75	$105.80
7 purchase totals =	$905.73		$972.2274	$972.23	$972.15	$972.20