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	$200.63	13.470%	$227.6549	$227.65	$227.65	$227.70
Purchase #2	$225.55	10.811%	$249.9342	$249.93	$249.95	$249.90
Purchase #3	$196.83	8.310%	$213.1866	$213.19	$213.20	$213.20
Purchase #4	$37.30	5.657%	$39.4101	$39.41	$39.40	$39.40
Purchase #5	$87.92	5.223%	$92.5121	$92.51	$92.50	$92.50
Purchase #6	$127.97	11.537%	$142.7339	$142.73	$142.75	$142.70
Purchase #7	$184.37	6.668%	$196.6638	$196.66	$196.65	$196.70
7 purchase totals =	$1,060.57		$1,162.0956	$1,162.08	$1,162.10	$1,162.10