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	$46.43	4.787%	$48.6526	$48.65	$48.65	$48.70
Purchase #2	$145.46	13.439%	$165.0084	$165.01	$165.00	$165.00
Purchase #3	$193.61	11.234%	$215.3601	$215.36	$215.35	$215.40
Purchase #4	$161.39	13.196%	$182.687	$182.69	$182.70	$182.70
Purchase #5	$169.91	11.831%	$190.0121	$190.01	$190.00	$190.00
Purchase #6	$178.84	9.673%	$196.1392	$196.14	$196.15	$196.10
Purchase #7	$48.31	7.495%	$51.9308	$51.93	$51.95	$51.90
7 purchase totals =	$943.95		$1,049.7902	$1,049.79	$1,049.80	$1,049.80