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	$69.27	5.614%	$73.1588	$73.16	$73.15	$73.20
Purchase #2	$75.26	4.119%	$78.36	$78.36	$78.35	$78.40
Purchase #3	$184.30	5.462%	$194.3665	$194.37	$194.35	$194.40
Purchase #4	$170.39	4.673%	$178.3523	$178.35	$178.35	$178.40
Purchase #5	$191.42	4.246%	$199.5477	$199.55	$199.55	$199.50
Purchase #6	$226.72	3.191%	$233.9546	$233.95	$233.95	$234.00
Purchase #7	$81.74	10.773%	$90.5459	$90.55	$90.55	$90.50
7 purchase totals =	$999.10		$1,048.2858	$1,048.29	$1,048.25	$1,048.40