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	$169.30	3.802%	$175.7368	$175.74	$175.75	$175.70
Purchase #2	$248.83	11.669%	$277.866	$277.87	$277.85	$277.90
Purchase #3	$63.93	3.672%	$66.2775	$66.28	$66.30	$66.30
Purchase #4	$88.82	8.549%	$96.4132	$96.41	$96.40	$96.40
Purchase #5	$74.88	7.699%	$80.645	$80.65	$80.65	$80.60
Purchase #6	$160.38	3.450%	$165.9131	$165.91	$165.90	$165.90
Purchase #7	$224.86	10.624%	$248.7491	$248.75	$248.75	$248.70
7 purchase totals =	$1,031.00		$1,111.6007	$1,111.61	$1,111.60	$1,111.50