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	$57.74	3.689%	$59.87	$59.87	$59.85	$59.90
Purchase #2	$220.97	11.305%	$245.9507	$245.95	$245.95	$246.00
Purchase #3	$29.29	6.431%	$31.1736	$31.17	$31.15	$31.20
Purchase #4	$238.68	6.612%	$254.4615	$254.46	$254.45	$254.50
Purchase #5	$237.80	11.627%	$265.449	$265.45	$265.45	$265.40
Purchase #6	$94.33	4.732%	$98.7937	$98.79	$98.80	$98.80
Purchase #7	$189.83	3.673%	$196.8025	$196.80	$196.80	$196.80
7 purchase totals =	$1,068.64		$1,152.5010	$1,152.49	$1,152.45	$1,152.60