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	$34.36	3.499%	$35.5623	$35.56	$35.55	$35.60
Purchase #2	$79.46	5.370%	$83.727	$83.73	$83.75	$83.70
Purchase #3	$190.42	4.126%	$198.2767	$198.28	$198.30	$198.30
Purchase #4	$199.59	5.147%	$209.8629	$209.86	$209.85	$209.90
Purchase #5	$115.46	10.705%	$127.82	$127.82	$127.80	$127.80
Purchase #6	$181.45	9.731%	$199.1069	$199.11	$199.10	$199.10
Purchase #7	$165.72	10.822%	$183.6542	$183.65	$183.65	$183.70
7 purchase totals =	$966.46		$1,038.0100	$1,038.01	$1,038.00	$1,038.10