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	$50.25	7.689%	$54.1137	$54.11	$54.10	$54.10
Purchase #2	$240.28	7.834%	$259.1035	$259.10	$259.10	$259.10
Purchase #3	$51.54	7.162%	$55.2313	$55.23	$55.25	$55.20
Purchase #4	$134.86	7.295%	$144.698	$144.70	$144.70	$144.70
Purchase #5	$97.53	4.681%	$102.0954	$102.10	$102.10	$102.10
Purchase #6	$202.48	13.419%	$229.6508	$229.65	$229.65	$229.70
Purchase #7	$164.52	4.758%	$172.3479	$172.35	$172.35	$172.30
7 purchase totals =	$941.46		$1,017.2406	$1,017.24	$1,017.25	$1,017.20