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	$59.82	4.581%	$62.5604	$62.56	$62.55	$62.60
Purchase #2	$31.40	10.524%	$34.7045	$34.70	$34.70	$34.70
Purchase #3	$243.63	8.407%	$264.112	$264.11	$264.10	$264.10
Purchase #4	$112.46	13.509%	$127.6522	$127.65	$127.65	$127.70
Purchase #5	$167.69	9.570%	$183.7379	$183.74	$183.75	$183.70
Purchase #6	$132.56	7.380%	$142.3429	$142.34	$142.35	$142.30
Purchase #7	$193.26	9.418%	$211.4612	$211.46	$211.45	$211.50
7 purchase totals =	$940.82		$1,026.5711	$1,026.56	$1,026.55	$1,026.60