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	$88.59	7.501%	$95.2351	$95.24	$95.25	$95.20
Purchase #2	$96.25	3.475%	$99.5947	$99.59	$99.60	$99.60
Purchase #3	$83.55	7.540%	$89.8497	$89.85	$89.85	$89.80
Purchase #4	$66.51	7.377%	$71.4164	$71.42	$71.40	$71.40
Purchase #5	$65.59	4.158%	$68.3172	$68.32	$68.30	$68.30
Purchase #6	$203.58	3.825%	$211.3669	$211.37	$211.35	$211.40
Purchase #7	$126.98	3.131%	$130.9557	$130.96	$130.95	$131.00
7 purchase totals =	$731.05		$766.7357	$766.75	$766.70	$766.70