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	$192.81	11.223%	$214.4491	$214.45	$214.45	$214.40
Purchase #2	$178.33	10.308%	$196.7123	$196.71	$196.70	$196.70
Purchase #3	$211.53	3.755%	$219.473	$219.47	$219.45	$219.50
Purchase #4	$67.61	7.674%	$72.7984	$72.80	$72.80	$72.80
Purchase #5	$138.72	6.589%	$147.8603	$147.86	$147.85	$147.90
Purchase #6	$241.28	9.665%	$264.5997	$264.60	$264.60	$264.60
Purchase #7	$34.26	9.399%	$37.4801	$37.48	$37.50	$37.50
7 purchase totals =	$1,064.54		$1,153.3729	$1,153.37	$1,153.35	$1,153.40