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	$62.65	6.525%	$66.7379	$66.74	$66.75	$66.70
Purchase #2	$67.25	6.703%	$71.7578	$71.76	$71.75	$71.80
Purchase #3	$84.97	5.194%	$89.3833	$89.38	$89.40	$89.40
Purchase #4	$64.28	12.213%	$72.1305	$72.13	$72.15	$72.10
Purchase #5	$64.92	8.583%	$70.4921	$70.49	$70.50	$70.50
Purchase #6	$74.39	8.536%	$80.7399	$80.74	$80.75	$80.70
Purchase #7	$218.93	11.220%	$243.4939	$243.49	$243.50	$243.50
7 purchase totals =	$637.39		$694.7354	$694.73	$694.80	$694.70