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	$162.42	7.736%	$174.9848	$174.98	$175.00	$175.00
Purchase #2	$149.78	5.734%	$158.3684	$158.37	$158.35	$158.40
Purchase #3	$39.46	6.860%	$42.167	$42.17	$42.15	$42.20
Purchase #4	$200.76	12.709%	$226.2746	$226.27	$226.25	$226.30
Purchase #5	$67.32	7.729%	$72.5232	$72.52	$72.50	$72.50
Purchase #6	$217.29	5.841%	$229.9819	$229.98	$230.00	$230.00
Purchase #7	$139.49	13.560%	$158.4048	$158.40	$158.40	$158.40
7 purchase totals =	$976.52		$1,062.7047	$1,062.69	$1,062.65	$1,062.80