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	$193.97	7.279%	$208.0891	$208.09	$208.10	$208.10
Purchase #2	$67.35	9.237%	$73.5711	$73.57	$73.55	$73.60
Purchase #3	$89.82	12.370%	$100.9307	$100.93	$100.95	$100.90
Purchase #4	$239.74	10.874%	$265.8093	$265.81	$265.80	$265.80
Purchase #5	$94.80	7.245%	$101.6683	$101.67	$101.65	$101.70
Purchase #6	$231.69	4.864%	$242.9594	$242.96	$242.95	$243.00
Purchase #7	$99.98	5.333%	$105.3119	$105.31	$105.30	$105.30
7 purchase totals =	$1,017.35		$1,098.3398	$1,098.34	$1,098.30	$1,098.40