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	$148.96	4.815%	$156.1324	$156.13	$156.15	$156.10
Purchase #2	$58.75	4.285%	$61.2674	$61.27	$61.25	$61.30
Purchase #3	$159.72	12.479%	$179.6515	$179.65	$179.65	$179.70
Purchase #4	$103.43	13.423%	$117.3134	$117.31	$117.30	$117.30
Purchase #5	$142.49	7.741%	$153.5202	$153.52	$153.50	$153.50
Purchase #6	$162.95	10.866%	$180.6561	$180.66	$180.65	$180.70
Purchase #7	$187.71	5.552%	$198.1317	$198.13	$198.15	$198.10
7 purchase totals =	$964.01		$1,046.6727	$1,046.67	$1,046.65	$1,046.70