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	$178.41	10.120%	$196.4651	$196.47	$196.45	$196.50
Purchase #2	$224.60	11.807%	$251.1185	$251.12	$251.10	$251.10
Purchase #3	$151.59	3.197%	$156.4363	$156.44	$156.45	$156.40
Purchase #4	$91.62	8.180%	$99.1145	$99.11	$99.10	$99.10
Purchase #5	$139.87	7.553%	$150.4344	$150.43	$150.45	$150.40
Purchase #6	$55.78	5.653%	$58.9332	$58.93	$58.95	$58.90
Purchase #7	$18.77	5.103%	$19.7278	$19.73	$19.75	$19.70
7 purchase totals =	$860.64		$932.2298	$932.23	$932.25	$932.10